Saturday, March 25, 2006

New, obscure, and nearly extinct rodents of South America, and…. when fossils come alive

My phd thesis - which, may I remind you, is all about Lower Cretaceous predatory dinosaurs, focusing in particular on the basal tyrannosauroid Eotyrannus - consists of six chapters. The good news is that chapter 5 (devoted to enigmatic large theropods) is nearing completion, and chapter 6 (on Yaverlandia) is already just about done. That still leaves tidying up on the other chapters, plus various tasks like running a few analyses, inserting a few more figures here and there, and so on. But I’m getting there. Thecocoelurus, Juravenator, Calamosaurus, Becklespinax and Valdoraptor are the animals that I’ve been thinking about the most I suppose, and I’d post on them if there was enough time. But there isn’t, so here’s another post devoted to rodents. To think this was all initiated by a tea card featuring a jerboa.

Though new rodents are described from all over the place (yes, even from North America and Europe*), I had a recollection of the greatest percentage coming from South America. And indeed there are quite a few (note that some of the following don’t have common names), with a randomly-selected list of my favourites being…

-- Michoacan deer mouse Osgoodomys banderanus Hooper & Musser, 1964, a narrow-skulled Mexican murid described as a new species of Peromyscus but given its own genus (named after Osgood [see previous post: Osgood, Fuertes and mice that swim and mice that wade]) in 1980. It’s the species featured in the photo above (and, yes, I do know that Mexico isn't in South America, but let’s pretend that I've now expanded the scope to be ‘Latin America’).
-- the Candango or Brasilia burrowing mouse Juscelinomys candango Moojen, 1965, a semi-fossorial murid discovered in 1960, known from 9 specimens, last collected in 1990, and now possibly extinct (the Brazilian site where it was discovered was destroyed and built on).
-- Olrog’s chaco mouse Andalgalomys olrogi Williams & Mares, 1978, an Argentinian sigmodontine murid.
-- Abrawayaomys ruschii Cunha & Cruz, 1979, a spiny Brazilian sigmodontine known from a handful of specimens.
-- Abrocoma boliviensis Glanz & Anderson, 1990, a Bolivian chinchilla rat known from two specimens, one collected in 1926 and the other in 1955.
-- Amphinectomys savamis Malygin et al., 1994, an amphibious Peruvian murid known from a single specimen collected in 1991.
-- Pearsonomys annectans Patterson, 1992, a semi-fossorial Chilean murid.
-- Microakodontomys transitorius Hershkovitz, 1993, a Brazilian murid known from a single specimen (collected in 1986).
-- Salinomys delicatus Braun & Mares, 1995, an Argentinian phyllotine sigmodontine with proportionally long feet and large ears.
-- Roig’s Chaco mouse Andalgalomys roigi Mares & Braun, 1996, another Argentinian sigmodontine.
-- Black or Koopman’s tree porcupine Coendou koopmani Handley et al., 1992, a Brazilian tree porcupine with short, dark fur. A similar form from Ecuador, differing in being speckled with white or yellow, was reported by Emmons (1999) and may be a new, as yet unnamed, species.
-- Orces fishing mouse Chibchanomys orcesi Jenkins & Barnett, 1997, an amphibious ichthyomine murid endemic to the Ecuadorian Parque Nacional Cajas.
-- Cuscomys ashaninka Emmons, 1999, a large Peruvian chinchilla rat [see post ‘Giant furry pets of the Incas’] discovered in 1997.
-- Akodon aliquantulus Monica Díaz et al., 1999, an Argentinian sigmodontine known from two specimens collected in 1993. The smallest member of its genus.
-- Tapecomys primus Anderson & Yates, 2000, a Bolivian phyllotine sigmodontine collected in 1991.
-- Coendou ichillus Voss & da Silva, 2001, an Ecuadorian tree porcupine first collected in 1936.
-- Coendou roosmalenorum Voss & da Silva, 2001, a small tree porcupine first collected in 1996 and named for Marc van Roosmalen and his son Tomas. Van Roosmalen is well known in South American mammalogy for the multiple new monkey species he has discovered.
-- Abrocoma uspallata Braun & Mares, 2002, an Argentinian chinchilla rat with larger ears and a longer tail than related species. Known only from a single specimen collected in 1995 (incidentally, if you've read the previous post on abrocomids, go look again some time: I’ve had to update it in view of this discovery and others).
-- Thomasomys ucucha Voss, 2003, a sigmodontine (first collected in 1980) from the Cordillera Oriental of Ecuador.

There are many more. Note as usual that the discovery date of a taxon is not necessarily the same as the date as when it was first named or recognised as new. Not all new rodents are South American: other discovery hotspots include Madagascar, Australia, New Guinea, and Borneo and elsewhere in SE Asia. Because rodents are typically small and inconspicuous it follows that a steady trickle of dull little mouse-type things should be continually discovered and described as new taxa, but it wouldn’t be accurate to think that all new rodents are like this. Three of the animals listed above are tree porcupines, and these are all fairly big rodents with head and body lengths of about 30 cm. Abrocomids are also large, with head and body lengths typically exceeding 30 cm.

Discoveries of entirely new animals are very cool of course, but they’re actually mundane and entirely ordinary. If you follow the literature it is very easy to become either overwhelmed or bored by the incredible number of new species that get described, even among tetrapods. Descriptions of new rodent, frog and lizard species appear routinely within technical journals – as in, a few every month. Perhaps slightly more interesting, and certainly more unusual, are those cases where species originally described as fossils have later turned out to be still extant. Such animals are often described as ‘living fossils’, but that’s a bit silly given that virtually all extant species have a record going back many thousands of years at least, thus making their presence in the fossil record inevitable (for more on this area go see Are Sumatran rhinos really ‘living fossils’?). Anyway, classic examples of this sort of thing include the following.

-- Goosebeak or Cuvier’s beaked whale Ziphius cavirostris: described as a fossil in 1823 but realised in 1872 to be the same thing as beached specimens reported as early as 1826 but given different names.
-- Bush dog Speothos venaticus: named as a fossil in 1839 [which explains why its generic name means ‘cave wolf’], and first described in living form in 1843. The same person, Danish naturalist Peter Wilhelm Lund, described both the fossil and living animals, but failed to realise they were the same thing: he named the living animals Icticyon, and this name was for used for Speothos until well into the 20th century.
-- False killer whale Pseudorca crassidens: described as a fossil in 1846 and described from modern-day strandings in 1862.
-- Mountain pygmy possum Burramys parvus: described from Pleistocene owl pellets in 1896 but found alive in a ski lodge in the Australian Alps in 1966.
-- Chacoan peccary Catagonus wagneri: named as a fossil in 1930, and found alive in 1974.
-- Bulmer’s fruit bat Aproteles bulmerae: described as a fossil in 1977 and reported from modern-day bones in 1980, then feared extinct, but since rediscovered alive.

Relatively little known is that the generic name for white-tailed and mule deers, Odocoileus, was originally coined for a fossil (a premolar found in a Pennsylvanian cave), and later transferred to the extant species when they and the tooth were found to belong to the same genus. Among rodents, there are, similarly, a few cases where fossil species have later been discovered extant, but because the animals concerned are obscure and poorly known, the relevant cases have gone under-reported.

-- A new fossil murid from Flores was described as Floresomys naso by Musser (1981). The generic name was preoccupied by a fossil Mexican sciuravid, so Musser et al. (1986) renamed this taxon Paulamys naso. A single live individual was reported in 1991 (Kitchener et al. 1991).
-- In 1887, Herluf Winge described multiple fossil murids from the Brazilian Lagoa Santa caves, and among them was a species he called Scapteromys labiosus. In 1980 this species, now referred to the crimson-nosed rat genus Bibimys, was reported to be extant within the same region (Voss & Myers 1991).
-- Hesperomys simplex was described from the Lagoa Santa caves by Winge in 1887, but also reported by him as occurring in modern-day owl pellets, and thus still extant. A Paraguayan murid named Oryzomys wavrini was described in 1921, and was shown by Voss & Myers (1991) to be the same thing as Hesperomys simplex, the name currently used for this taxon being Pseudoryzomys simplex. It’s sometimes called the ratos-do-mato (Nowak 1999).
-- A living species from Uruguay and Brazil, described in 1955 as Holochilus magnus, was shown by Voss & Carleton (1993) to be the same thing as another Pleistocene fossil species named by Winge in 1887, Hesperomys molitor. Restudy of this murid showed that it was distinct from both Holochilus (the semiaquatic web-footed rats) and Hesperomys (nowadays synonymous with Calomys, the vesper mice) and thus deserving of its own genus, so today this species is called Lundomys molitor.

All of these ‘prehistoric survivors’ were known originally from Pleistocene or Holocene fossils, so their presence in modern times has only ever extended their geological range by a million years or so, at most (in some cases – such as that of Paulamys naso – by just a few thousand years).

Changing the subject somewhat, among modern-day mammals there are only two species whose discovery has extended the geological range of their clade by an amount of more than a few million years, and note that we’re no longer talking about members of the same species being present across a longer span of time than originally thought. One of them has lately been in the news. The first is the so-called Monito del Monte or Colocolo Dromiciops australis, described in 1894 and classified as a didelphid. In 1955 however, Reig pointed out that Dromiciops was almost identical to Microbiotherium from the Miocene, and it is now widely agreed that Dromiciops is a living representative of Microbiotheriidae, a South American marsupial clade named in 1887 and with a fossil record that doesn’t extend beyond the Lower Miocene. Dromiciops has no fossil record, so a ghost lineage of about 20 million years has to be invoked for the group. Incidentally, exactly how microbiotheriids fit into marsupial phylogeny is a hotly debated topic that would require a post all its own.

The second ‘late survivor’ brings us back to rodents: it’s the Laotian kha-nyou Laonastes aenigmamus, described last year as representing an entirely new hystricognath lineage, the Laonastidae (Jenkins et al. 2005). But - how cool is this - Dawson et al. (2006) have shown that Laonastes is in fact a living representative of Diatomyidae, a group otherwise known only as fossils, and with a fossil record that doesn’t extend beyond the Upper Miocene. So we now have to extrapolate a ghost lineage for diatomyids that extends from the Upper Miocene to the present: that’s about 7-5 million years, so not that long, but… even so. As Dawson et al. (2006) note, late survivors that represent ‘the reappearance of taxa after a lengthy hiatus in the fossil record’ are termed ‘Lazarus taxa’, and Dromiciops and Laonastes can both be described this way. As it happens I was going to post on Lazarus taxa in the near future anyway: not because of rodents but because of late-surviving Mesozoic basal synapsids. To say more would give the game away. Think also of temnospondyls, choristoderes and sphenosuchians.

And there’s more to say on Laonastes too: it’s exciting, not just in being a Lazarus taxon, but in being a specialised, highly cryptic member of a bizarre and specialised relict community. Tied to a specific unusual habitat, it is one of a suite of recently recognised species whose distribution may actually extend beyond Lao PDR. More on that soon. Err, maybe when I’ve finished the thesis. Oh yes, the thesis.

*North America recently yielded the Sonoma tree vole Arborimys pomo Johnson & George, 1991, and Europe the Bavarian pine vole Microtus bavaricus König, 1962. The latter species was thought extinct following its post-1962 disappearance, but was rediscovered in 2000.

The picture above is of Osgoodomys banderanus, and was borrowed from the Instituto de Biología site.

Refs - -

Dawson, M. R., Marivaux, L., Li, C.-k., Beard, K. C. & Metais, G. 2006. Laonastes and the “Lazarus effect” in Recent mammals. Science 311, 1456-332.

Emmons, L. H. 1999. Neotropical Rainforest Mammals: A Field Guide (Second Edition). University of Chicago Press (Chicago & London).

Jenkins, P. D., Kilpatrick, C. W., Robinson, M. F. & Timmins, R. J. 2005. Morphological and molecular investigations of a new family, genus and species of rodent (Mammalia: Rodentia: Hystricognatha) from Lao PDR. Systematics and Biodiversity 2, 419-454.

Kitchener, D. L., How, R. A. & Maharadatunkamnsi. 1991. Paulamys sp. cf. P. naso (Musser, 1981) (Rodentia: Muridae) from Flores Island, Nasu Tenggara, Indonesia – description from a modern specimen and a consideration of its phylogenetic affinities. Records of the Western Australian Museum 15, 171-189.

Musser, G. G. 1981. The giant rat of Flores and its relatives east of Borneo and Bali. Bulletin of the American Museum of Natural History 169, 67-176.

- ., van de Weerd, A. & Strasser, E. 1986. Paulamys, a replacement name for Floresomys Musser, 1981 (Muridae), and new material of that taxon from Flores, Indonesia. American Museum Novitates 2850, 1-10.

Nowak, R. M. 1999. Walker’s Mammals of the World, Sixth Edition (two volumes). The Johns Hopkins University Press (Baltimore and London).

Voss, R. S. & Carleton, M. D. 1993. A new genus for Hesperomys molitor Winge and Holochilus magnus Hershkovitz (Mammalia, Muridae): with an analysis of its phylogenetic relationships. American Museum Novitates 3085, 1-39.

- . & Myers, P. 1991. Pseudoryzomys simplex (Rodentia: Muridae) and the significance of Lund’s collections from the caves of Lagoa Santa, Brazil. Bulletin of the American Museum of Natural History 206, 414-434.

Tuesday, March 21, 2006

Osgood, Fuertes, and mice that swim and mice that wade

The manuscript on Crato turtles has been completed and submitted, the Galve vertebrates manuscript has been completed (to all intent and purposes), and the review of IUP’s The Carnivorous Dinosaurs has been completed (again, to all intent and purposes). So, finally, I’m hard at work on the phd, and once more deeply immersed in the world of basal tyrannosauroids. But having spent the better part of the day coding characters I think I will allow myself some blog time. If you think I’m going to post about Guanlong, Dilong, or even Eotyrannus, well: you don’t know me very well do you?

If you like the idea of being steeped in the lore of natural history research, then the literature on African amphibious murids provides rich pickings. Take the discovery of the obscure Ethiopian mouse Nilopegamys plumbeus, collected in 1927 by a field assistant of Wilfred H. Osgood on a tributary of the Blue Nile in north-eastern Ethiopia. Osgood (1875-1947) gained his reputation as an ornithologist and specialized during the 1890s in oology, but in 1897 he joined the then US Bureau of Economic Ornithology and Mammalogy (later to become the US Biological Survey) and embarked on significant collecting trips to California and Alaska. He later founded the Cooper Ornithological Club, and in 1909 joined the Field Museum of Natural History in Chicago. It was while based there that he made his best-known contributions: those published during the 1920s and 30s on the mammals of Africa (particularly Ethiopia) and South America (particularly Chile), and in particular on the rodents. In 1927, Osgood took part in an expedition jointly funded by the Field Museum and the Chicago Daily News.

In the field with Osgood was Louis Agassiz Fuertes (1874-1927), one of the most talented and revered of late 19th/early 20th century natural history artists (though he wasn’t just an artist, as he also lectured). Predominantly interested in birds, Fuertes - like Osgood - had explored Alaska in the late 1890s but later traveled widely across the Americas and Africa. He illustrated countless books, magazines and museum murals. And, yes, he was named after the Harvard professor and naturalist Louis Agassiz.

During that 1927 field trip, it was Fuertes’ job to draw the specimens obtained by Osgood’s party. Presented with the new rodent later named Nilopegamys, the sketch Fuertes produced is the only illustration that depicts a fresh specimen. It was also one of his last illustrations because, on returning home to the USA in August of that year, he was killed when a train struck his car at Potter’s Crossing, Unadilla (New York). The illustrations in the car at the time – which included the Nilopegamys sketch – were thrown from the vehicle during the collision.

Osgood (1928) described Nilopegamys as an entirely new sort of murid for Africa: as an amphibious swimmer most like the South American fish-eating rats Ichthyomys. But Nilopegamys was clearly not as specialized for amphibious life as are the ichthyomyines, and furthermore Osgood’s description was brief and without thorough comparisons to some other tropical African murids. Consequently it was suggested during the 1960s that Nilopegamys wasn’t a distinct taxon, and that it should be sunk into synonymy with Colomys goslingi, the Velvet rat. A long-limbed murid with an impressive array of whiskers, Colomys is amphibious and hunts for arthropods, worms and molluscs along stream and swamp edges. The consensus opinion became that Osgood and Fuertes had been incorrect about the validity of Nilopegamys, and, in time, it disappeared from the textbooks.

But it turns out that this decision was rash. Redescribing Nilopegamys in 1995, Julian Kerbis Peterhans and Bruce Patterson showed that Nilopegamys was clearly morphologically distinct from Colomys, and certainly worthy of generic recognition. While both genera are similar in their velvety fur and sharp demarcation between dark upperside and white underside, they differ in that Nilopegamys is larger, with broader feet that possess hairy margins, and with proportionally smaller ear pinnae. The two also differ in the arrangement of pads on their feet, in the number of roots their molars have, in the sizes of their foramen magnum, and in other details (Kerbis Peterhans & Patterson 1995). The features that distinguish Nilopegamys from Colomys suggest that it is more specialized for aquatic life than Colomys is. In essence, it seems to be evolving toward an ichthyomyine-like condition, and it certainly possesses several of the characters that Voss (1988) listed as being correlated with amphibious habits in murids (dense and soft fur, enlarged hind feet, enlarged braincase, reduced visual and olfactory senses etc.).

Nilopegamys and Colomys are both different from another tropical African form, Malacomys: the long-footed rats, big-eared swamp rats or long-eared marsh rats. Poorly known, but apparently ranging throughout most of central Africa, Malacomys looks like a mouse on stilts, at least when it’s not crouching. Because these amphibious mice differ in so many of their anatomical details (and share few detailed, uniquely derived characters), Kerbis Peterhans & Patterson (1995) suggested that the similarities apparent between them are due to convergence. It would be nice, however, to test this by plugging them into a phylogeny. However, people are only just starting to work on parsimony-based murid phylogenies, and I’m not aware of any that incorporate Nilopegamys or Colomys. Malacomys at least appears to represent a distinct lineage within the so-called core murine clade, not too distant phylogenetically from Mus and Apodemus (Steppan et al. 2005), but there are suggestions that it is not monophyletic and that two distinct lineages may be included. McKenna & Bell (1997) listed Nilopegamys and Colomys adjacent to one another, but I suspect that this is an admission of ignorance more than anything else. The fantastically-named Congo forest mouse Deomys ferrugineus (sometimes called the Link mouse) is another similar long-footed form of uncertain phylogenetic position.

You might be surprised to hear that there are amphibious mice at all. But not only are there several amphibious African mice, there are in fact multiple murid lineages around the world whose members swim, wade, or forage in aquatic environments. South America is home to an endemic amphibious murid radiation, Ichthyomyini, that consists of five genera: three whose members are generally termed fish-eating rats (Ichthyomys, Antomys and Neusticomys), as well as Rheomys (the Central American water mice) and Chibchanomys (the Chibchan water mice). Only distantly related to these are Holochilus (the web-footed rats), Nectomys (the Neotropical water rats) and the recently discovered, poorly known Lundomys and Amphinectomys, all of which seem to be part of the rice rat [oryzomyine] group. Then there’s Scapteromys (the ‘rata acuatica’), which seems to be closest to the deeply weird Kunsia and Bibymys (all three genera have been united by some workers in a little clade termed Scapteromyini). Australasia has an assemblage of amphibious murids that includes Hydromys (the beaver rats) and Crossomys (the earless water rat), plus a number of genera where experts disagree as to whether the animals are actually amphibious or not. And there are others elsewhere in the world.

What makes the African taxa special is that, not only have they so far failed to become as well adapted for amphibious life as have murids elsewhere (like the ichthyomyines, or Hydromys or Crossomys), but they might also be doing something that murids elsewhere are not. For, while Colomys, Malacomys and Deomys are even less specialized for amphibious life than Nilopegamys is, they are specialized in one, peculiar way: recall that, earlier on, I characterized them as ‘mice on stilts’. Noting that these genera possess particularly narrow, elongate feet, Kerbis Peterhans & Patterson (1995) showed that they formed a distinct cluster in terms of foot length : breadth, when compared with other murids. What might this mean? Unfortunately very very few published accounts discuss, describe or even mention the natural history and behaviour of these species, but a few do. While ichthyomyines and ichthyomyine-like murids are speedy swimmers that dart rapidly away underwater when threatened, Kerbis Peterhans & Patterson (1995) reported observations (made by Jonathan Kingdon and Ivan Sanderson) indicating that the stilt-legged mice really do use their long, narrow feet like stilts, wading around in shallow water. Such stilt-legged, wading mice seem unique to Africa.

Could it be that murids have evolved in this direction because there’s something unique about tropical African waterways that has allowed them to specialize in this way? One thing does spring to mind: the presence of amphibious shrews and otter-shrews, all of which are, also, uniquely African. Living alongside Colomys, Malacomys and Deomys are the shrews Ruwenzorisorex and Scutisorex, both of which reportedly exploit aquatic environments (though, to be honest, you wouldn’t know this from the literature). Murids are thought to have gotten into Africa relatively recently (about 6 million years ago), whereas the lipotyphlans have an African record going back as far as the Miocene.

Kerbis Peterhans & Patterson (1995) therefore suggested that ‘Prior or more successful exploitation of the ‘swimmer’ niche by lipotyphlans may have served to limit murid opportunities in this mode. Competition with lipotyphlans may also have driven the development of the ‘wader’ mode by central African forms’ (p. 346). Such amphibious lipotyphlans are entirely absent from South America, and this might then explain why ichthyomyines have radiated so extensively. But if this is true, what about Nilopegamys, which (as I said earlier) is an African form apparently evolving toward an ichthyomyine-like condition? Well, it inhabits the Ethiopian plateau (and is in fact one of about 30 mammal species endemic to this region (Yalden & Largen 1992)), where there are no amphibious lipotyphlans.

Oh well… back to the tyrannosaurs.

The illustration above is a John Gould painting of Hydromys, taken from here.

Refs - -

Kerbis Peterhans, J. C. & Patterson, B. D. 1995. The Ethiopian water mouse Nilopegamys Osgood, with comments on semi-aquatic adaptations in African Muridae. Zoological Journal of the Linnean Society 113, 329-349.

McKenna, M. C. & Bell, S. K. 1997. Classification of Mammals: Above the Species Level. Columbia University Press, New York.

Osgood, W. H. 1928. A new genus of aquatic rodents from Abyssinia. Field Museum of Natural History, Zoological Series 12 (15), 185-189.

Steppan, S. J., Adkins, R. M., Spinks, P. Q. & Hale, C. 2005. Multigene phylogeny of the Old World mice, Murinae, reveals distinct geographic lineages and the declining utility of mitochondrial genes compared to nuclear genes. Molecular Phylogenetics and Evolution 37, 370-388.

Voss, R. S. 1988. Systematics and ecology of ichthyomyine rodents (Muroidea): patterns of morphological evolution in a small adaptive radiation. Bulletin of the American Museum of Natural History 188, 259-493.

Yalden, D. W. & Largen, M. J. 1992. The endemic mammals of Ethiopia. Mammal Review 22, 115-150.

Friday, March 17, 2006

Giant furry pets of the Incas

If you’ve read Scott Weidensaul’s excellent book The Ghost With Trembling Wings (2002), you’ll recall the story of Louise Emmons and the giant Peruvian rodent she discovered. But before I get to that, let me say that The Ghost With Trembling Wings isn’t about ghosts at all, but about the search for cryptic or supposedly extinct species. Think thylacines, British big cats, Ivory-billed woodpeckers, Cone-billed tanagers, the resurrection of the aurochs, Night parrots, Richard Meinertzhagen and the Indian forest owlet. It begins with Weidensaul’s search for Semper’s warbler Leucopeza semperi, an enigmatic parulid endemic to St. Lucia, discovered in 1870 and last seen alive in 1969 (although with a trickle of post-1969 sightings, some reliable and some not so reliable). If you’re interested in the hunt for cryptic species and zoological field work and its history, it is mandatory that you obtain and read this inexpensive book.

Louise Emmons is a highly distinguished, experienced mammalogist who has worked on bats, tree shrews, cats big and small, and rodents, and is also the foremost expert on the mammals of the Neotropical rainforests (she wrote the only field guide to Neotropical rainforest mammals: Emmons 1999a). On 15th June 1997, while on an expedition to the northern Vilcabamba range of Cusco, Peru, she was walking along a forest track when, lying dead on the track in front of her, she discovered a big dead rodent. Pale grey, but handsomely patterned with a white nose and lips, and with a white blaze running along the top of its head, it was over 30 cm in head and body length, and with a tail over 20 cm long. Its broad feet, prominent and curved claws, large hallux, and palms and soles covered in small tubercles indicated that it was a tree-climbing species. A large bite wound on the neck indicated that it had recently been killed by a predator, probably a Long-tailed weasel Mustela frenata.

And it was entirely new: no one had ever recorded anything like it before. In her description of the new species, Emmons (1999b) named it Cuscomys ashaninka (meaning ‘mouse from Cusco, of the Ashaninka people’) and showed that it was a member of Abrocomidae. This is an entirely South American group previously known only from Abrocoma Waterhouse 1837, members of which are sometimes called rat chinchillas, chinchilla rats or chinchilliones, and from the Miocene fossil Protabrocoma Kraglievich 1927. Abrocoma is known from eight species (A. bennetti, A. boliviensis, A. cinerea, A. vaccarum, A. uspallata, A. budini, A. famatina and A. schistacea), among which A. boliviensis was only recognised in 1990 and A. uspallata in 2002 (Glanz & Anderson 1990, Braun & Mares 1996, 2002). Incidentally A. bennetti has 17 pairs of ribs – more than any other rodent. Abrocoma produces midden piles, and Pleistocene rodent middens from Chile have been identified by DNA analysis as having been produced by Abrocoma (Kuch et al. 2002).

Abrocomids are members of Hystricognathi, the rodent clade that includes Old World porcupines and the New World caviomorphs (New World porcupines, agoutis, pacas, cavies, pacaranas, capybaras, hutias, chinchillas, vizcachas and so on), and within this group they appear to be members of a clade that includes chinchillas and vizcachas.

So now there is a second extant abrocomid taxon, and it and Abrocoma are actually quite different. Species of the latter are specialized for life at high latitudes, and have short tails, a reduced hallux and inflated auditory bullae. They’re entirely terrestrial, inhabiting burrows among rocks, and are therefore like chinchillas, and convergent on degus and pikas. While Cuscomys shares derived characters with Abrocoma not present in other rodents, it’s larger, long-tailed and with features indicating a scansorial lifestyle. It’s convergent with climbing murids, like the cloudrunners Crateromys and cloud rats Phloeomys of the Philippines and the giant tree rats Mallomys of New Guinea (Emmons 1999b), and its striking coloration is much like that of the White-faced tree rat Echimys chrysurus (a member of the echimyid, or spiny rat, family: echimyids are hysticognaths, as are abrocomids, but they apparently belong to the octodontid-hutia clade, not to the chinchilla-vizcacha clade (Sánchez-Villagra et al. 2003)).

Here’s where this story becomes even cooler. During his 1912 Yale University-National Geographic expedition to the Inca ruins of Machu Picchu, Peru, George Eaton discovered that a number of different mammal species had been placed, in graves, alongside human bodies (Eaton 1916). They included familiar animals like dogs, llamas and guinea pigs, but also others that are far more obscure. Dwarf brockets were there (brockets Mazama are a group of small-bodied deer known from Mexico and South America), as were coro-coros (also called bamboo rats Dactylomys, coro-coros are arboreal members of Echimyidae), Mountain pacas Cuniculus taczonowskii*, AND an abrocomid that Eaton recognized as a new species. He named it Abrocoma oblativus.

*Eaton (1916) misidentified the Mountain pacas and thought that the Machu Picchu remains represented a new species that he called Agouti thomasi. Incidentally, the genus Cuniculus Brisson 1762 is the same animal as that more often called Agouti Lacépède 1799. The former name clearly has priority though.

Emmons’ discovery of Cuscomys ashaninka allowed her to determine that the abrocomid in the Machu Picchu graves wasn’t a species of Abrocoma as Eaton had thought, but a second member of Cuscomys, so it became renamed C. oblativus. Given what we now know of the life appearance of Cuscomys, it’s likely that C. oblativus was similar: strikingly patterned, and overall quite cute and cuddly. There’s the obvious implication here that Inca people were being buried with sacrified specimens of Cuscomys because they kept them as cuddly pets, though of course it’s also possible that the animals were kept as food. If C. ashaninka has been cryptic enough to remain undiscovered until 1997, can we be absolutely sure that C. oblativus is really extinct? No. While the graves containing C. oblativus have been dated to 1450-1532 AD (Emmons 1999b), even today the region surrounding Macha Picchu is sparsely inhabited, remote, and with a substantial cover of pristine cloud forest. There just isn’t any good reason why C. oblativus should have become extinct, so Emmons (1999b) suggested that it might still be extant, and awaiting rediscovery.

Here’s another interesting thing. Of those mammals found in the Inca tombs, Cuscomys was unknown to modern scientists, in its living state, until 1997. The dwarf brocket present there turned out to belong to a new species that wasn’t named until 1959 (when Hershkovitz named it Mazama chunyi*), and the coro-coros and mountain pacas present in the tombs have also proved to be cryptic and elusive. So the Incas knew mammals that remained unknown to modern science until the late 20th century, and in fact knew them well enough to capture them frequently, and perhaps keep them in semi-domesticated state. As Emmons noted ‘Macha Picchu hunters were evidently skilled at capturing cloud forest mammals that are not readily taken by our current collecting methods’ (1999b, p. 13). I know nothing of how Inca hunters tracked and caught the animals they did (nor do I have access to literature that might be informative on this subject), but it would be very interesting to know just how they were finding and catching these species. They must have had the most excellent, experienced field skills, and the most intimate knowledge of the species they were hunting.

*Mazama chunyi isn’t the only recently-recognised brocket species. M. permira, a dwarf island-endemic from Isla San José off Panama, wasn’t named until 1946, and M. bororo was named in 1996 after a specimen kept at Sao Paulo’s Sorocaba Zoo demonstrated the distinctiveness of this taxon (Duarte & Gianonni 1996). What might be a new species was recently reported by Trolle & Emmons (2004) for a specimen photographed by a camera trap in 2003.

PS - for the latest news on Tetrapod Zoology do go here.

The photo of the Cuscomys ashaninka holotype used above is from here.

Refs - -

Braun, J. K. & Mares, M. A. 1996. Unusual morphological and behavioural traits in Abrocoma (Rodentia: Abrocomidae) from Argentina. Journal of Mammalogy 77, 891-897.

- . & Mares, M. A. 2002. Systematics of the Abrocoma cinerea species complex (Rodentia: Abrocomidae), with a description of a new species of Abrocoma. Journal of Mammalogy 83, 1-19.

Duarte, J. M. B. & Gianonni, M. L. 1996. A new species of deer in Brazil (Mazama bororo). Deer Specialist Group Newsletter 13, 3.

Eaton, G. F. 1916. The collection of osteological material from Machu Picchu. Memoirs of the Connecticut Academy of Arts and Sciences 5, 1-96.

Emmons, L. H. 1999a. Neotropical Rainforest Mammals: A Field Guide (Second Edition). University of Chicago Press (Chicago & London).

- . 1999b. A new genus and species of abrocomid rodent from Peru (Rodentia: Abrocomidae). American Museum Novitates 3279, 1-14.

Glanz, W. E. & Anderson, S. 1990. Notes on Bolivian mammals. 7. A new species of Abrocoma (Rodentia) and relationships of the Abrocomidae. American Museum Novitates 2991, 1-32.

Kuch, M., Rohland, N., Betancourt, J. L., Latorre, C., Steppan, S. & Poinar, H. N. 2002. Molecular analysis of a 11,700 year-old rodent midden from the Atacama Desert, Chile. Molecular Ecology 11, 913-924.

Sánchez-Villagra, M. R., Aguilera, O. & Horovitz, I. 2003. The anatomy of the world’s largest extinct rodent. Science 301, 1708-1710.

Trolle, M. & Emmons, L. H. 2004. A record of a dwarf brocket from Madre de Dios, Peru. Deer Specialist Group Newsletter 19, 2-5.

Weidensaul, S. 2002. The Ghost With Trembling Wings. North Point Press (New York).

Sunday, March 12, 2006

The biggest eagle, part I

In a previous post (When eagles go bad) I mentioned Haast’s eagle, a giant extinct species from New Zealand that would have been capable of some awesome predatory behaviour. Here, we look at this species in more detail.

Until recently New Zealand truly was a land of birds. Inhabited by the 11 (or so) species of moa (future blog post to come on that), the long-beaked kiwis, snipes and snipe-rails, the bizarre adzebills, a variety of rails and coots, flightless ducks and geese, giant terrestrial owlet-nightjars, diminutive New Zealand wrens, and a motley assortment of crows, quails, mergansers, parrots, wattlebirds, thrush-like passerines, owls, honeyeaters and herons, it would appear to be the ideal place for birds of prey to evolve, and to take predatory advantage of this diverse avifauna. We now know that New Zealand was inhabited until very recent times by at least two such birds of prey, and both/all were specialised bird predators [an alleged third species, a sea eagle described from Chatham Island in 1973 and dubbed Haliaeetus australis, has proved to be a mis-labelled North American Bald eagle H. leucocephalus. A fourth species, the New Zealand falcon Falco novaeseelandiae, has survived to the present].

The first of the two bird predators was originally described as a very large harrier, and called Circus eylesi by Ron Scarlett in 1953. With large females perhaps weighing as much as 3 kg, this was a giant if it were a harrier: living species rarely weigh more than 700 g (Clarke 1990). Scarlett later regarded the bird as a giant goshawk however (a member of the genus Accipiter), a specialist bird-catcher adept at flying through tangled woodland habitats. Though the goshawk reidentification has become quite well known, new examination has demonstrated that the attribution of the species to Circus was correct. It really was a gigantic, bird-killing member of the group (and whether it is one or two species still remains contested).

The second New Zealand bird of prey was the biggest eagle EVER - the enormous Haast’s eagle Harpagornis moorei Haast 1872, a powerful forest giant that some experts have imagined as being something like the modern Harpy eagle Harpia harpyja. As will be discussed in part II, new data indicates that the generic name Harpagornis is invalid, but we won’t worry about that now [part II now available here].

Introducing Haast’s eagle

Haast’s eagle has been known to science since 1871, but until recently virtually nothing was known of how it may have lived, or how it was related to other kinds of eagles. Several publications on Haast’s eagle addressing these problems were produced by Richard Holdaway in the late 1980s and 1990s following his 3-volume doctoral dissertation and a huge amount of information on the bird was recently compiled by Trevor Worthy and Holdaway for their superb book The Lost World of the Moa. Go there if you are even vaguely interested; you won’t regret it.

The first Haast’s eagle material to be discovered by Europeans was found by Frederick Fuller at the moa excavation site at Glenmark swamp, Canterbury, in 1871. Johann Franz Julius Haast (1822-1887), director of the Canterbury Museum and noted expert on moa and other New Zealand birds, read a description of the species to the Philosophical Society of Canterbury in 1871, and published his description the following year (Worthy & Holdaway 2002). He named the bird after George Moore, the owner of Glenmark Station. This association of Haast’s eagle with moa immediately led to suggestions that it was a moa-hunter, and had perhaps come to feed on moa that had become trapped in the mud of the swamps.

Subsequent finds showed the eagle to be widely distributed on South Island and the southern half of North Island. However, even before its official extinction date, it seems to have been rare or absent from the eastern coast of central North Island (Horn 1983) and quite why it was never widely distributed in the northern half of North Island, which at this time was heavily forested and apparently ideal for the bird, remains a mystery. Like other giant birds of prey around the world, Haast’s eagle does not appear to have been common at any locality and its remains are not particularly abundant: only three complete skeletons are known, the most recently discovered being reported in 1990. This specimen was discovered at the bottom of a narrow vertical sinkhole and seems to have fallen accidentally to its death (Worthy & Holdaway 2002).

As in most birds of prey, female Haast’s eagles were larger than males. In estimated weight they were 10-13 kg and, though (in keeping with its probable forest-dwelling lifestyle) their wings were proportionally short, they still had a wingspan of around 2.6 m. The standing height of a female Haast’s eagle has been estimated as 1.1 m. Male Haast’s eagles, which were initially regarded as a separate species (H. assimilis Haast 1874), probably weighed 9-10 kg. For comparison, the largest living eagles, the Harpy Harpia harpyja, Philippine eagle Pithecophaga jefferyi and European Haliaeetus albicilla and Steller’s sea eagles H. pelagicus, rarely exceed 2.4 m in wingspan. Some female H. albicilla have been recorded with wingspans of 2.65 m and a large female H. pelagicus may reach 9 kg (Brown 1976, Burton 1989). Amongst living birds of prey, only condors exceed these measurements - the Andean condor Vultur gryphus possibly exceeding 3 m in wingspan and reaching 12 kg.

The skull of Haast’s eagle measures 15 cm in total length and is elongate, looking something like a stretched version of an Aquila skull, and without the tremendously deep beak seen in some forest eagles like Pithecophaga and Harpia. The skull is actually superficially rather like that of an Old World vulture and, unlike other aquiline eagles, the nostril in Haast’s eagle was partially closed-off by ossification around its rostral, dorsal and ventral margins. This recalls the presence of an accessory bony plate that covers part of the nostril opening in some of the larger Old World vultures. The legs and feet of Haast’s eagle were tremendously robust and powerful and appear well capable of dispatching very large prey. Its claws are massive, strongly curved and, with their external keratin sheath, would have reached 75 mm in length. A complete, thorough description of the osteology of Haast’s eagle was provided by Worthy & Holdaway (2002): the premiere source of information on this bird.

While some material dates Haast’s eagle to around 30,000 years before present, its youngest remains show that it was still around about 500 years ago, and it therefore most probably became extinct at around the same time as (or slightly before) the moa. Presumably, as moa hunting became more intense and moa became rarer and rarer, and as habitat degradation on New Zealand increased, Haast’s eagle became increasingly pressurised and eventually unable to sustain a population. A c. 300 year overlap of Haast’s eagle and humans therefore seems to have occurred (the Maori colonised New Zealand at around 850 years before present). Seeing as the Maori have legends of giant predatory birds - including of the sky-dwelling hokioi or hakuwai and the man-eating pou-kai - it has been tempting for writers to speculate that these legends do indeed refer to Haast’s eagle (Reed 1963, Hall 1994). Unfortunately the legends are far too vague for this to be confirmed, but it has led to some very interesting speculations (to be covered in part II).

Surprisingly, much as some people have continued to entertain notions of moa survival to the present day, there have been a number of suggestions that Haast’s eagle did not die out 500 years ago, but survived to within living memory. This idea is based on two lines of evidence: eyewitness accounts of large birds of prey, and reports of unusual unidentified bird calls of a particularly loud and startling nature. The calls were reported from Stewart Island as recently as 1961 and, because the animal making these nocturnal sounds was never seen, it was suggested by some that Haast’s eagle might have been the vocaliser. Needless to say, more likely candidates are on offer and Miskelly (1987) suggested that New Zealand snipe (Coenocorypha) might actually be the culprit.

Alleged eyewitness accounts from recent times are few, and restricted to the 1860s. Haast actually saw what he thought was a giant eagle in the Canterbury mountains, and a large bird that walked into his tent one night was also suggested to be a giant eagle. Even more incredible is Charlie Douglas’ reported shooting of two giant eagles in the Landsborough Valley, both of which, reportedly, had wingspans of 3 m or so. Worthy & Holdaway (2002, p. 335) noted that Douglas was ‘a meticulous observer, he did not seek publicity, and he certainly never claimed that he had seen the “extinct” eagle’. It’s an incredible report, and one that can’t be verified.

To come in a Part II: what kind of eagle was Haast’s eagle?; what did it look like?; and what, and how, did it hunt?

The above picture - which doesn't really depict a Haast's eagle of course - is from

Refs - -

Brown, L. 1976. Eagles of the World. David & Charles (Newton Abbot/London/Vancouver).

Burton, P. 1989. Birds of Prey. Gallery Books (London).

Clarke, R. 1990. Harriers of the British Isles. Shire Natural History (Princes Risborough, UK).

Hall, M. A. 1994. Thunderbirds - the living legend! (2nd edition). Privately published (Minneapolis).

Horn, P. L. 1983. Subfossil avian deposits from Poukawa, Hawkes Bay, and the firat record of Oxyura australis (Blue-billed duck) from New Zealand. Journal of the Royal Society of New Zealand 13, 67-78.

Miskelly, C. M. 1987. The identity of the hakawai. Notornis 34, 95-116.

Reed, A. W. 1963. Treasury of Maori Folklore. A. H. & A. W. Reed (Wellington, NZ).

Worthy, T. H. & Holdaway, T. H. 2002. The Lost World of the Moa. Indiana University Press (Bloomington, Indiana).

Saturday, March 11, 2006

It’s not a rhinogradentian: it’s the most fantastic jerboa, Euchoreutes

It’s funny how things work out. Today I am obsessed with rodents. Why? Most of my day was spent clearing out an old loft, and while rummaging through decades of accumulated rubbish I came across multiple copies of old Brooke Bond picture card albums, and among them one of my favourites: Tunnicliffe’s Asian Wild Life. Brooke Bond pictures cards were given away free inside boxes of tea (the tea-producing branch of the company later became known as PG Tips) and, for a small fee, collectors could send off for an album. Hugely influential to young people that grew up in tea-drinking households during the 1960s and 70s, many of the series were devoted to natural history, and they are fondly remembered by many people who work today in the biological sciences. They explain my fascination with the artwork of Peter Scott, Charles Tunnicliffe and Maurice Wilson.

While, mostly, I looked after the albums that I inherited from my mother – who collected the cards herself as a girl – there were a few that I unfortunately defaced and mutilated, Asian Wild Life among them. So today I’m happy to have back in my hands not one, but two, pristine, completed albums. Like several of the Brooke Bond picture cards series, Asian Wild Life was both written and illustrated by the fantastic Charles F. Tunnicliffe (1901-1979). And there is always one picture in particular that fascinated me, and today still does: it’s Tunnicliffe’s painting (reproduced above) of two Yarkand jerboas Euchoreutes naso, bounding together across the steppes of north-west China.

Euchoreutes has to be one of the oddest-looking rodents and, years later, when I learnt about the rhinogradentians (on which I will post soon), I wondered if Euchoreutes wasn’t really a jerboa at all, but in fact a wayward rhinogradentian, perhaps related to the Earwing Otopteryx volitans. Even the binomial – Euchoreutes naso – is suggestive of some link with rhinogradentians given that the latter group includes the nasobemes (genus Nasobema). Like earwings, Euchoreutes has ridiculously enormous ears, and its alternative name is the Long-eared jerboa. If anything, Tunnicliffe’s painting actually doesn’t make the ears appear large enough: in photos, the ears look to be about as long as the entire body.

And in body length, Euchoreutes is just 70-90 mm long. That’s small, but not as small as the Baluchistan pygmy jerboa Salpingotus michaelis: with a body length of 36-47 mm it’s the smallest living rodent (it’s also relatively new to science, having only been discovered in 1966 and named in 1973). At the other end of the scale, some species of Allactaga (the four- and five-toed jerboas) exceed 260 mm in body length, and can then have a tail over 300 mm long. Getting back to Euchoreutes, it’s odd not just for its large ears, but also for its unusually long snout. It does however resemble most other jerboas in having proportionally small forelimbs and tremendously elongate hindlimbs.

Like all jerboas (well.. nearly all: read on), Euchoreutes has fused metatarsals. Is metatarsal fusion a synapomorphy for the group? There’s a problem with that: the Five-toed dwarf jerboa Cardiocranius paradoxus lacks metatarsal fusion. Is this because it’s the most basal jerboa, because it exhibits a character reversal, or because it’s not a jerboa at all? While few phylogenetic studies incorporate it (it is a very obscure and little-studied species), it is usually implied in classifications that it’s down at the base of the jerboa clade (properly called Dipodidae).

Though pedal digits I and V are reduced in Euchoreutes, they are still present. This contrasts with the dipodine jerboas Paradipus, Dipus, Stylodipus, Eremodipus and Jaculus, all of which lack lateral digits and are tridactyl. Their elongate, fused metatarsi thus bears three distinct distal condyles and look, at least superficially, remarkably like the tarsometatarsi of birds. This similarity has not been lost on ornithologists (Rich 1973) and is a remarkable case of convergent evolution. If the proximal end of the metatarsus were broken off (and this bit is the giveaway, as it of course shows the presence of tarsals charactestically mammalian in form and number), I suspect that even some experienced zoologists would be fooled into misidentifying a jerboa metatarsus as an avian one. Sadly I don’t have many jerboa leg skeletons lying around so cannot test this idea. Incidentally, most of the cervical vertebrae in jerboas are fused together as well, and in some dwarf jerboas the first three dorsal vertebrae are also fused together, and to the fused cervicals. I don’t know why this is, but it might be to prevent dislocation or jarring during the violent acceleration and deceleration incurred during leaping and bounding.

And on the subject of leaping and bounding, jerboa feet are clearly specialised for saltation (jumping). With body lengths of mostly around 100 mm, jerboas can cover about 3 m in a single leap. This is a neat and useful trick if you want to cross large distances on hot sand, but of course jerboas are mostly nocturnal, and the predominant function of saltation in jerboas is to move quickly away from predators. One species – the Rough-legged jerboa Dipus sagitta – exhibits particularly interesting predator-avoidance behaviour: it not only leaps from predators, but, as it leaps, grabs at over-hanging foliage with its teeth and forelimbs, and then clambers into the vegetation to hide (Hanney 1975).

Specialised as they are for impoverished steppes, sub-deserts and deserts, jerboas have apparently benefited from desertification in some regions (Duplaix & Simon 1977). This probably only applies to tolerant generalists among the group, however, and certainly doesn’t work for Euchoreutes. It reportedly declined by about 50% during the 1990s (Nowak 1999) and is regarded as endangered.

Phylogenetic studies demonstrate that Euchoreutes really is a jerboa, and not a rhinogradentian, and it’s traditionally been allocated its own ‘subfamily’ called Euchoreutinae Lyon, 1901 within the jerboa family Dipodidae Fischer de Waldheim, 1817. Whether Euchoreutes is actually a member of either of the two dipodid clades that have been recognised in phylogenetic studies of this group - Dipodinae and Allactaginae (Shenbrot 1992) - remains uncertain. One study of dipodid phylogeny based on cranial characters (Dempsey 1991) didn’t include Euchoreutes as no skulls were available for examination, which isn’t surprising given that only a handful of specimens are present in museums worldwide (Nowak 1999). Classifications have generally listed Euchoreutinae as separate from Dipodinae and Allactaginae, but only because the ‘subfamily’ rankings demand that each be treated as equivalent in rank. So exactly how does Euchoreutes fit into dipodid phylogeny? That’s a good question, and I’d be interested to know if it’s yet been answered.

Dipodidae appears to have evolved in the Miocene from ‘a taxon at the sicistine/zapodine [viz, birch mouse/jumping mouse] level of evolutionary dental development’ (Martin 1994, p. 99). Incidentally, Dipodidae is sometimes used for the clade that includes birch mice and jumping mice, as well as jerboas. However most rodent workers seem to favour the use of the family-level name Zapodidae for birch mice and jumping mice, with Dipodidae restricted to jerboas proper. Dipodids + Zapodids = Dipodoidea. The name Dipodidae obviously comes from ‘dipodes’ meaning ‘two-footed’, the term apparently used for jerboas by Herodotus (writing some time around 430 B.C.).

On the subject of dipodid phylogeny I can’t resist mentioning Krasnov & Shenbrot’s (2002) study of co-evolution between fleas and jerboas. It’s an interesting study in that they found no good correlation between flea phylogeny and jerboa phylogeny: the distribution of fleas on their jerboa hosts depends instead on ecological and geographical factors. You might argue that this is predictable, given that parasites like ticks, lice and fleas mostly switch between hosts that inhabit similar environments, rather than those that are closely related. Bed bugs Cimex, for example, are well known for parasitizing humans, but before this they were bird and bat parasites which ‘transferred their attentions to man when he began to live in caves and stayed with their new host when he moved away from the forests into other living quarters’ (Andrews 1976, p. 162). Unfortunately for my research on Euchoreutes, it wasn’t included in Krasnov & Shenbrot’s (2002) study as it generally lacks fleas entirely!

So there you have it. I should have said at the beginning why I have a thing about rodents right now. Firstly, I’m quite excited about the new paper in Science showing that the recently described Laotian rodent Laonastes isn’t actually an entirely new taxon, but in fact belongs to a group otherwise known only as fossils, the Diatomyidae. I have a blog post planned on that, and about other, similar cases from the rodent world (go here to see it). Then there are the tie-ins with what I was saying in previous posts about Amazonian fragmentation and Pleistocene refugia, as rodents are involved in these stories too. Right, I need to get back to those Crato turtles. For the latest news on Tetrapod Zoology do go here.

Tunnicliffe’s painting of Euchoreutes shown above is from…

…. where you can see the complete run of Asian Wild Life picture cards.

Refs - -

Andrews, M. L. A. 1976. The Life That Lives on Man. Faber & Faber, London.

Dempsey, M. A. 1991. Cranial foramina and relationships of dipodoid rodents. Unpubished B. A. thesis, Baruch College of The City University of New York.

Duplaix, N. & Simon, N. 1977. World Guide to Mammals. Octopus Books, London.

Hanney, P. W. 1975. Rodents: Their Lives and Habits. David & Charles, Newton Abbot.

Krasnov, B. R. & Shenbrot, G. I. 2002. Coevolutionary events in the history of association between jerboas (Rodentia: Dipodidae) and their flea parasites. Israel Journal of Zoology 48, 331-350.

Martin, R. A. 1994. A preliminary review of dental evolution and paleogeography in the zapodid rodents, with emphasis on Pliocene and Pleistocene taxa. In Tomida, Y., Li, C. K. & Setoguchi, T. (eds) Rodent and Lagomorph Families of Asian Origins and Diversification. National Science Museum Monographs 8, 99-113.

Nowak, R. M. 1999. Walker’s Mammals of the World, Sixth Edition, Volume II. The Johns Hopkins Univesity Press (Baltimore and London).

Shenbrot G.I., 1992. A cladistic approach to the analysis of phylogenetic relationships among dipodid rodents (Rodentia; Dipodoidea). Archives of the Zoological Museum, Moscow State University 29, 176‑200.

Rich, P. V. 1973. A mammalian convergence on the avian tarsometatarsus. The Auk 90, 676-677.

Thursday, March 09, 2006

The late survival of Homotherium confirmed, and the Piltdown cats

Some of the most fascinating, illuminating insights into extinct animals come from data recorded by the people who saw them. We might be sad that the Pleistocene megafauna are gone, but at least our ancestors painted, carved and sculpted representations of them. I promised in a previous post that I'd add my 'Piltdown cats' text. Here it is: it's not news - in fact the main scoop here is now well known, but in the interests of recycling old text for a new audience, I thought I may as well post it. Incidentally, I used the term 'Piltdown cat' before Chris Moiser noted the journalistic employment of the term 'Piltdown puss' in his recent book, but that's another story.

In 1896, in the French cave of Isturitz, a 16-cm long statuette of a big cat was discovered. Initially interpreted as a representation of a cave lion, it was reinterpreted by Vratislav Mazak (1970) as more likely being a depiction of the sabre-tooth Homotherium latidens (a species sometimes dubbed the scimitar cat). Like a homothere, but unlike a lion, the statuette (which has since been lost) has a short tail and a deepened lower jaw. If the statuette is meant to depict Homotherium, it provides us with some new information on the life appearance of this cat, as it appears to be decorated with small spots, and to have a pale underside. As Rousseau (1971a, 1971b) described, there are also other Palaeolithic pieces of cave art that appear to depict homotheres.

The problem though is that the Isturitz statuette (and other pieces of evidence) is somewhere around 30,000 years old, and the last accepted datum for skeletal material of Homotherium in Europe is 300,000 years BP (Adam 1961) [though see below]. This significant discrepancy therefore suggests that Homotherium survived in Europe for much later than thought but, given that this has until now been based on artwork, the area has remained controversial. As Shuker (1989) wrote: ‘Were the above works of Palaeolithic art nothing more than inaccurate or idealized depictions of cave lions, or do they comprise genuine proof that the extraordinary scimitar cat was a contemporary of our ancestors for a far longer period of time than hitherto believed?’.

A new young homothere record

In March 2000 the fishing vessel UK33 trawled a partial felid lower jaw from an area SE of the Brown Bank in the North Sea, an area previously known for yielding Pleistocene and Holocene fossil mammals. As described by Jelle Reumer et al. (2003), the jaw is from a Homotherium latidens, and what is especially significant is that radiocarbon analysis dates it to 28,000 years BP. As Reumer et al. note, this is about the same age as the Isturitz statuette and therefore confirms the long-suspected late survival of this felid in Europe.

Incidentally, the climate in northern Europe at this time would have been quite harsh - the Devensian Glaciation was at its height between 25,000 and 15,000 years BP, and at this time northern Britain as far south as Yorkshire was covered by an ice sheet. Cold tundra and steppe environments occurred to the south and east of this ice sheet, and only cold-tolerant species could have lived in the area now occupied by the North Sea. Reindeer were living in Cambridgeshire, Polar bears in London, and Musk ox in Wiltshire. Homotherium latidens must also have therefore been a cold-tolerant species. Given that Homotherium species also dwelt in temperate and tropical environments (in Asia homotheres are known as far south as Java), this was clearly a highly adaptable felid.

The Piltdown cats

Prior to Reumer et al.’s discovery there were a number of British homothere fossils which were initially regarded as coming from late glacial deposits, and thus being somewhere around 13,000-11,000 years BP in age (i.e., as young as the youngest possible age for the youngest American material). Most famously they include a single canine from Robin Hood Cave, the largest cave of the Creswell Crag complex at Derbyshire, discovered in 1876. Describing the tooth in 1877, William Boyd Dawkins, the pioneering geologist and expert on Palaeolithic man, suggested that it may have been introduced into the cave by humans, as it appeared to bear both the marks of a flint tool, and an incomplete perforation at its base. On balance though, Dawkins concluded that the tooth suggested late survival of Homotherium in Britain. This idea has been mentioned by other workers and it led Kurtén (1968) to suggest that H. latidens survived in Britain for far longer than it did in mainland Europe, or in other words that Britain acted as a refugium for this disappearing species. Pleistocene refugia? Hang on: didn’t I talk about those in the previous blog?

Although it may have been separated from mainland Europe during one or more of the Pleistocene interglacials (namely during part of the Ipswichian Interglacial, between c. 130,000-70,000 years BP), the English Channel did not flood until c. 9000 years BP, so any homothere living in Britain between 13,000 and 11,000 years ago could still have walked to mainland Europe (Stuart 1974, Yalden 1982).

It is of further interest to note that, had a hypothetical homothere population become isolated in interglacial Britain, it may only have lasted for about 1000 years before become extinct due to inbreeding. Recent modelling work on population viability in large Pleistocene carnivorans (O'Regan et al. 2002) has shown that even glacial refugia the size of the Iberian and Italian peninsulas were not big enough for large felids to survive in when these populations became isolated, as they apparently did during the Pleistocene glaciations (though see previous blog, and I have more on this subject to add soon). Lack of space during these times may therefore have promoted extinction, an issue that is particularly poignant today as large carnivorans find themselves restricted to increasingly smaller islands of suitable habitat.

Returning to the Robin Hood Cave tooth, recent work indicates that Dawkins' initial suspicions were right. The fact that the tooth had been altered by humans indicates that it probably was traded and carried around by them long after its original owner had died (Charles & Jacobi 1994). Furthemore, the specimen was apparently discovered on one of the four days on which the senior archaeologist in charge of the site - Tom Heath - was absent. Consequently it is not surprising that hoaxing has been suggested at various times, and Yalden (1999) compared the Robin Hood Cave homothere to the Piltdown fossils (which I'll also be blogging on at some stage, due to mostly over-looked links with the world of British dinosaurs). This remains an unproven assertion however, and Kenneth Oakley's (1980) discovery that the tooth differs in its fluorine, uranium and nitrogen content from all other British homothere fossils has been used as evidence both for and against its being a hoax. Given these problems though it has been recommended that this record be ignored.

British homotheres are also known from the early Pleistocene site of Dove Holes near Buxton, Derbyshire, a site that also yielded giant hyaenas, straight-tusked elephants and southern mammoths (Dawkins 1903), but is today occupied by a municipal rubbish dump (Yalden 1999). Middle Pleistocene British homotheres are known from the cavern infill site near Westbury-sub-Mendip, Somerset (Bishop 1982). Finally, the Kent’s Cavern teeth - initially thought to be late Pleistocene - come from a cave that also contains older Pleistocene fossils, and it is now thought that they are also middle Pleistocene.

The figure of the Isturitz statue reproduced above is taken from Michel Raynal’s website….

Refs - -

Adam, K. D. 1961. Die Bedeutung der pleistozanen Saugetier-Faunen Mitteleuropas fur die Geschichte des Eiszeitalters. Stuttgarter Beitrage zur Naturkunde 78, 1-34.

Bishop, M. J. 1982. The mammal fauna of the early Middle Pleistocene cavern infill site of Westbury-sub-Mendip Somerset. Special Papers in Palaeontology 28, 1-108.

Charles, R. & Jacobi, R. M. 1994. The Lateglacial fauna from Robin Hood Cave, Cresswell: a re-assessment. Oxford Journal of Archaeology 13, 1-32.

Dawkins, W. B. 1903. On the discovery of an ossiferous cavern of Pliocene age at Dove Holes, Buxton (Derbyshire). Quarterly Journal of the Geological Society, London 59, 105-133.

Kurtén, B. 1968. Pleistocene Mammals of Europe. Weidenfeld & Nicolson (London).

Mazak, V. 1970. On a supposed prehistoric representation of the Pleistocene scimitar cat, Homotherium Farbrini, 1890 (Mammalia; Machairodontinae). Zeitschrift fur Saugertierkunde 35, 359-362.

Oakley, K. 1980. Relative dating of the fossil hominids of Europe. Bulletin of the British Museum (Natural History), Geology 34, 1-63.

O'Regan, H. J., Turner, A. & Wilkinson, D. M. 2002. European Quaternary refugia: a factor in large carnivore extinction? Journal of Quaternary Science 17, 789-795.

Reumer, J. W. F., Rook, L., Van Der Borg, K., Post, K., Mol, D. & De Vos, J. 2003. Late Pleistocene survival of the saber-toothed cat Homotherium in northwestern Europe. Journal of Vertebrate Paleontology 23, 260-262.

Rousseau, M. 1971a. Un félin à canine-poignard dans l’art paléolithique? Archéologia 40, 81-82.

Rousseau, M. 1971b. Un machairodonte dans l’art aurignacien? Mammalia 35, 648-657.

Shuker, K. P. N. 1989. Mystery Cats of the World. Robert Hale (London).

Stuart, A. J. 1974. Pleistocene history of the British vertebrate fauna. Biological Reviews 49, 225-266.

Yalden, D. W. 1982. When did the mammal fauna of the British Isles arrive? Mammal Review 12, 1-57.

Yalden, D. W. 1999. The History of British Mammals. Poyster Natural History (London).

Pleistocene refugia and late speciation: are extant bird species older than we mostly think?

I learnt today that knuckle-walking is painful, despite practice. I learnt that the British dinosaurs manuscript is still not submitted, that Jaime Headden is one of the most hard-working and reliable people on the planet, and that some people should leave well alone on the subject of Loch Ness monsters. I learnt that my review of Newton’s Encyclopedia of Cryptozoology has been published, though not in a form I totally approve of. And after reviewing other people’s manuscripts on Cretaceous birds, I immersed myself in the salamander literature once more (plethodontids and more on olms to come here soon). One thing led to another, and while checking Wolfgang Wüster’s recent publications I came across Wüster et al.’s response to Gosling & Bush – itself a response to an earlier article by Wüster et al. entitled ‘Tracing an invasion: landbridges, refugia, and the phylogeography of the Neotropical rattlesnake’. And so it begins: as we’ll see, it didn’t take long to veer well off target.

Climatic changes affect the distributions of organisms. This assertion is self-evident, not controversial, and indeed observable within a human lifetime. So given that the planet has experienced major fluctuations in climate within the recent geological past, it follows that well-vegetated habitats were fragmented during the dry cycles of the Pleistocene, and that previously contiguous animal populations became divided. For the purposes of this discussion, this fragmentation had two results: (1) that populations became restricted to refugia – that is, islands of surviving forested habitat; and (2) that speciation was encouraged and accelerated during this time (driving so-called Late Pleistocene Origins, and resulting in the LPO model). So that’s the theory: the ‘glacial refugium’ theory (Rand 1948, Stewart & Lister 2001).

I feel that this view of Pleistocene environmental change is logical and, at face value, well supported. It’s become well accepted to the extent that it’s become the stuff we find in textbooks (e.g. Wiens 1991). But interesting things are happening, and it’s after reading the recent papers on rattlesnake phylogeography that I decided to post to my blog on this. First, I went to the bird literature, as there is an awful lot of it on LPO. If you’re most interested in the rattlesnakes, prepare to be disappointed.

As a nerdy teenager reading all I could on animals, the view I grew up with was that extant birds had speciated during the Pleistocene, and that passerines in particular provided excellent support for LPO. Indeed, the LPO hypothesis has been mostly driven by studies on passerine speciation (Brodkorb 1960). However, this view has come under attack. Genetic data on speciation rates in passerines, published within the last 10 or so years, does NOT support the LPO model.

By looking at recently diverged taxa among North American passerine clades (including grackles, tits, parulids, thrashers and icterids), Klicka & Zink (1997) found that genetic divergence rates actually indicated splits rather older than they’d need to be to satisfy the LPO model: on average, the data suggested Late Pliocene divergence times occurring at about 2.5 million years ago. They determined this by assuming molecular clock rates of 2% per million years however, and herein lies the Achilles heel of their study, as there is considerable doubt as to the idea that genetic changes continue at a clock-like rate. They acknowledged this, and only compared taxa thought to have similar mutation rates. Arbogast & Slowinski (1998) produced a rebuttal arguing that the 2% divergence rate was inaccurate and that Klicka & Zink’s speciation dates were therefore erroneous, but reanalysis still didn’t produce inferred speciation rates young enough to satisfy the LPO model (Klicka & Zink 1998). As Klicka & Zink (1997) state ‘These results contradict the expectations of the LPO model. Overall, these data reflect a protracted history of speciation throughout the Pleistocene and Pliocene’ (pp. 1666-1667), and they termed the LPO model ‘a failed paradigm’. Other genetic studies have also found that extant bird species are actually pretty old (e.g. Zink & Slowinski 1995, Avise & Walker 1998, Avise et al. 1998).

This is very interesting from the palaeontological perspective – it means that by far the majority of passerines aren’t modern/Pleistocene novelties, but have actually been around for a while. Indeed the only taxon found by Klicka & Zink (1997) to be a novelty of this sort is the Timberline sparrow* Spizella taverneri: it seems to have diverged from S. breweri about 35,000 years ago.

* By the way America, your sparrows aren’t sparrows at all, but buntings. That’s a subject for a future blog.

What do the fossils say about this? Well that’s an interesting question, as different palaeornithologists have held conflicting perspectives on this issue. Taken at face value, the fossil record seems mostly to support the LPO model, given that Pleistocene bird fossils are unique to the Pleistocene. Brodkorb (1960) concluded that this was for real, and that few bird species crossed the end-Pleistocene boundary (yes yes, I know we’re still in the Pleistocene, but bear with me here).

Conversely though, others have argued that Pleistocene ‘species’ aren’t demonstrably distinct from Holocene ones – they might only be given different species name because of convention. A review of Pleistocene ‘species’ from Europe showed that the characters used to differentiate Pleistocene ‘species’ from modern ones were mostly vague and unsatisfactory assertions about size or robustness (Stewart 2002). One of the most important factors resulting in the recognition of a new Pleistocene taxon proved to be its age.. yes, that’s right: because it was from the Pleistocene, it must have been a new species. However, this is perhaps an unduly negative view. Tyrberg (2002) found that ‘few, if any, avian species are of Late Pleistocene age [DN: meaning that they’re older] while at least half of the extant Palearctic bird species have their origins in the Pliocene’ (p. 281). If he’s right, then the fossil data is in agreement with what the molecular workers report, and we should not be surprised when extant species are reported from the Pliocene, as they sometimes are.

But – hold on – extant species haven’t just been reported from the Pliocene, but also from the Miocene. Should we be taking this seriously too? Tyrberg (2002) reminds us of the case of Archaeotrogon venustus, an archaeotrogonid that persists in the fossil record for something like 14 million years. Assuming that all the fossils identified as belonging to this species really do represent the same animal (see previous blog on cryptic diversity), this is the longest range recorded for a bird. It indicates that ‘reports of extant species in the Late Miocene should not be rejected out of hand as is usually done’ (Tyrberg 2002, p. 287).

Now, this makes things even more interesting. I’m thinking New Guinea. Why? Many bird genera there – particularly paradisaeids and ptilonorhynchids – have bizarre disjunct distributions. The three similar Paradisaea species P. rubra, P. guilielmi and P. decora are found in the Moluccas (to the west of New Guinea) and in extreme eastern New Guinea, but nowhere in between. The similar astrapia species Astrapia nigra and A. rothschildi live in the Arfak and Tamrau mountains (to the extreme west) and on the Huon Peninsula (to the extreme east), respectively. How can these disjunct distributions be explained? Heads (2001a) argued that the birds must be the products of vicariance: the areas where they occur were formerly close, but as the microterranes moved, the birds have simply been ultra-sedentary and gone with them.

While there are very good reasons for thinking that these birds really are this sedentary (while many birds are great at dispersing, a great many others simply aren’t [Diamond 1981]), I used to think that this just couldn’t be right as there was no way the bird genera, let alone the species, could possibly be old enough. Well, now I’m not so sure. The key tectonic events seem to have occurred in the Miocene, and Heads concluded that the original non-disjunct distribution of the birds must really have dated from this time. Passerines aren’t the only New Guinean taxa with these distributions by the way – it’s present in plants and other groups too (Heads 2001a, b, c, d, 2002).

My plan originally was to discuss how Neotropical rattlesnake phylogeography has actually supported the concept of glacial refugia (that’ll have to be Part II: a post to come in future), then to go from there to the proposed Pleistocene fragmentation of Amazonia. But because birds don’t support the LPO model, they have ended up providing no support for this model, and in fact work on the timing of avian speciation has gone hand-in-hand with criticisms of the refugium theory.

So that’s the ‘bird’s-eye view’ of the area. The ‘rattlesnake’s-eye view’ is somewhat different, and that, as I said, will have to come in another post. For the latest news on Tetrapod Zoology do go here.

The picture above is from here.

Refs - -

Arbogast, B. S. & Slowinski, J. B. 1998. Pleistocene speciation and the mitochondrial DNA clock. Science 282, 1955a.

Avise, J. C. & Walker, D. 1998. Pleistocene phylogeographic effects on avian populations and the speciation process. Proceedings of the Royal Society of London B 265, 457-463.

- . , Walker, D. & Johns, G. C. 1998. Speciation durations and Pleistocene effects on vertebrate phylogeography. Proceedings of the Royal Society of London B 265, 1707-1712.

Brodkorb, P. 1960. How many bird species have existed? Bulletin of the Florida State Museum, Biological Sciences 5 (3), 41-56.

Diamond, J. 1981. Flightlessness and fear of flying in island species. Nature 293, 507-508.

Heads, M. 2001a. Birds of paradise, biogeography and ecology in New Guinea: a review. Journal of Biogeography 28, 893-925.

- . 2001b. Birds of paradise (Paradisaeidae) and bowerbirds (Ptilonorhynchidae): regional levels of biodiversity and terrane tectonics in New Guinea. Journal of Zoology 255, 331-339.

- . 2001c. Regional patterns of biodiversity in New Guinea plants. Botanical Journal of the Linnean Society 136, 67-73.

- . 2001d. Birds of paradise, vicariance biogeography and terrane tectonics in New Guinea. Journal of Biogeography 29, 261-283.

- . 2002. Regional patterns of biodiversity in New Guinea animals. Journal of Biogeography 29, 285-294.

Klicka, J. & Zink, R. M. 1997. The importance of recent ice ages in speciation: a failed paradigm. Science 277, 1666-1669.

- . & Zink, R. M. 1998. Pleistocene speciation and the mitochondrial DNA clock: response to Arbogast & Slowinski. Science 282, 1955a.

Rand, A. L. 1948. Glaciation, an isolating factor in speciation. Evolution 2, 314-321.

Stewart, J. R. 2002. The evidence for the timing of speciation of modern continental birds and the taxonomic ambiguity of the Quaternary fossil record. In Zhou, Z. & Zhang, F. (eds). Proceedings of the 5th Symposium of the Society of Avian Paleontology and Evolution. Science Press (Beijing), pp. 259-280.

- . & Lister, A. M. 2001. Cryptic northern refugia and the origins of the modern biota. Trends in Ecology & Evolution 16, 608-613.

Tyrberg, T. 2002. Avian species turnover and species longevity in the Pleistocene of the Palearctic. In Zhou, Z. & Zhang, F. (eds). Proceedings of the 5th Symposium of the Society of Avian Paleontology and Evolution. Science Press (Beijing), pp. 281-289.

Wiens, J. A. 1991. Evolurionary biogeography. In Brooke, M. & Birkhead, T. (eds) The Cambridge Encyclopedia of Ornithology. Cambridge University Press (Cambridge), pp. 156-161.

Zink, R. M. & Slowinski, J. B. 1995. Evidence from molecular systematics for decreased avian diversification in the Pleistocene Epoch. Proceedings of the National Academy of Sciences 92, 5832-5835.

Saturday, March 04, 2006

When salamanders invaded the Dinaric Karst: convergence, history, and reinvention of the troglobitic olm

It is a very good time to be interested in salamanders. Partly because of my reading-up on other areas of direct interest (like cryptic diversity [see previous post], the discovery of new species, declines in global biodiversity, Cretaceous biogeography, radical homoplasy, polymorphism, and evolutionary reversals), I am returning again and again to the salamander literature. Mostly, these studies are about plethodontids, where a lot of really neat research is being done. I will post to the blog about most of this at some stage (if you can’t wait that long see Hanken 1999, Parra-Olea et al. 2001, Chippindale et al. 2004, Mueller et al. 2004 and Min et al. 2005 to see where I’m coming from [update: go here for part I on plethodontids]).

It’s not a plethodontid (it’s a proteid), but one of the most unusual and interesting of amphibians has to be the Olm (Proteus anguinus), an unusual long-bodied cave-dwelling salamander from SE Europe. Olms were the first specialised cave-dwelling animals (so-called stygobionts or troglobites) to be discovered, they were traditionally identified as dragon larvae by local people, and they remain mysterious and the source of controversy, debate and discovery. I’ve had a special affinity for olms since seeing them (live) in the former Yugoslavia in 1987, and after a colleague published a brief article on them in 2004 I ended up compiling and publishing my olm-related thoughts. In the interests of re-cycling that text I reproduce it here, in updated form.

What might be the most fascinating fact concerning olms is the most poorly-known and least mentioned one: the 1986 discovery of a surface-dwelling olm, described in 1994 by Boris Sket and Jan Willem Arntzen. So olms aren’t just ‘unusual long-bodied cave-dwelling salamanders’ – they now exist in two forms, the cave-dwelling White olm Proteus anguinus anguinus and the surface-dwelling Black olm or Brown olm P. a. parkelj. Unlike the unpigmented nominal form with its skin-covered eyes, P. a. parkelj (presently known only from Bela Krajina in SE Slovenia) is dark brown or black and has externally visible (albeit small) eyes. Because White olms produce melanin when kept in sunlight (and are thus not albinistic as sometimes implied), the difference in colour between the two forms is not unexpected. However, there are also other, more important differences separating the two. P. a. parkelj differs from the nominal form in also having a proportionally shorter, broader and more muscular head, fewer teeth, a proportionally longer body and a proportionally shorter tail and limbs (Sket & Arntzen 1994).

Most of the features which distinguish P. a. parkelj from P. a. anguinus are plesiomorphies [= features not unique to olms, but present also in related salamanders] and hence P. a. parkelj may be the ancestor of the White olm. Having said that, one of the most interesting contentions made recently about olms (Sket 1997) is that the different cave-dwelling olm populations may have evolved independently from different ancestral populations. If this is correct it may be that the different White olm populations represent different species which resemble one another by convergent evolution, and which have partly or mostly fused as they have met up within the Dinaric karst system. Sket (1997) thought that morphological and genetic differences observed among olms might provide support for this view and, ironically, if correct it would mean that several old species names proposed for different cave-dwelling olms might need to be resurrected. Fitzinger (1850) named seven new olm species within his genus Hypochthon (H. zoissii, H. schreibersii, H. freyeri, H. haidingeri, H. laurentii, H. xanthostictus and H. carrarae), though given that the type localities for some of them were just a few km apart, it’s unlikely that they really were distinct taxa.

It’s worth saying that olms almost certainly aren’t ancient relicts, or living fossils. In fact, they must be young and recently evolved. Why? During the Pleistocene, the Dinaric area was so close to areas that were fully glaciated that temperature there must have been at or below freezing. This is far too cold for olms, which require temperatures of 6-18ºC for their eggs and larvae to develop (and toward the upper end of that range is best). Furthermore, karstification and the development of underground streams only began in the Dinaric region during the late Pliocene at the earliest, apparently. In view of these problems, olms either (1) survived in surface waters in the region, where summer temperatures were just about tolerable (but where winter temperatures would have made life difficult), or (2) moved into the area from a warmer, southerly refuge (Griffiths 1996, Sket 1997). It isn’t yet known which was the case: more research is needed. Whatever, troglobitic olm populations must have evolved within the last 10,000 years or so, and presumably the specialised troglobitic morphology of living olms evolved during this time. Similarly recent invasions of cave systems appear to have occurred among various troglobitic fishes.

As mentioned earlier, olms were the earliest troglobites to be discovered. While it’s been stated on occasion that the species was discovered as recently as 1875 (Laňka & Vít 1985, Keeling 2004), olms first became widely known in 1689 when Baron Johann Weichard Valvasor wrote about the animals in his book on the Yugoslavian province of Carniola (on which see below). However, it wasn’t until the mid-1700s that the animals become the subject of proper scientific debate. At this time Slovenian scientist Giovanni Scopoli ‘discovered’ olms and realized just how extraordinary they were (Scopoli 1772). He planned to describe the animal scientifically and enhance his reputation by doing so. We know that Scopoli sent pictures of olms to Carl von Linne and that Linne and Scopoli disagreed as to whether the animals were a distinct new genus (Scopoli’s view), or the juveniles of something else (Linne’s view). However, the Austrian anatomist J. N. Laurenti became very interested in olms at the same time as Scopoli (apparently because of a specimen Scopoli had sent to one of the Laurenti’s friends) and, in 1768, published the first scientific description of the species (Laurenti 1768). This is the ‘official’ date of the White olm’s scientific discovery. Laurenti’s choice of generic name for the olm (Proteus) is based on the Greek god Proteus but it is not Proteus’ shape-shifting ability that Laurenti had in mind, but rather his status as shepherd of sea creatures. Laurenti’s work on the olm did not actually become that well known and it was Karl von Schreibers’ work of the 1790s and early 1800s which made olms well known among scientists.

Olm distribution has been the subject of much confusion and speculation. Presently, olms are restricted to the Dinaric Karst, a region that extends from the Soca (formerly the Isonzo) River (near Trieste) in SE Friuli-Venezia Giulia, Italy to the Trebišnica River in eastern Herzogovina. In between Italy and Herzogovina, olms also occur in southern Slovenia, southern Croatia and parts of Bosnia. Little known is that the species has been recorded from localities in France (Moulis) and Germany (Harz). These extralimital records are all apparently due to human introduction however. They are also found in the Parolini Grotto, Vicenza, northern Italy, but their presence here is due to human introduction also. Of further interest, the locality mentioned by Valvasor (1689) – the spring of Lintvern, near Vrhnika – is actually outside of the Dinaric Karst, and is unlike the other areas inhabited by olms in geology and geomorphology. It seems that Valvasor made the logical (but incorrect) assumption that Lintvern (which is a garbled form of the German word Lindwurm, meaning dragon) was so named because it was the source of olms (which were fancifully regarded as dragon larvae at the time).

Keeling (2004) implied that Carniola (note: not Carinola) might be the Italian part of the olm’s range and also wondered if Carniola might still be part of Austria. Carniola is today called Kranjska and was controlled by Austrian royalty until 1918 (consequently, the ruling classes there spoke German until the 20th century). It is today part of central Slovenia and is thus not either the Italian part of the olm’s range, nor an Austrian extension of the species’ range.

Bizarrely, olms were traded during Victorian times as exotic pets and were apparently available in Britain as such (which raises the remote possibility that they might have been introduced to British cave systems in the same way that they were in French, German and Italian ones). During the 1950s it was reported that olms were present in the Carpathian karst of eastern Serbia, and in 1960 a team of speleologists from Ljubljana led an expedition to the region to investigate this possibility. They didn't find any olms there, and nor has anyone else since.

Olms have been horrendously over-collected for scientific use and were also apparently collected by farmers for use as pig food. One of the greatest problems facing olms today is metal poisoning caused by industrial pollution and a number of populations have declined as a result of such. P. a. parkelj is under strict legal protection. Olms have been protected in Slovenia at least since 1949 and elsewhere in their range they are widely recognized as deserving protection.

Finally, regarding diet and breeding, olms apparently mostly detect their prey using chemical clues and the detection of water currents but they also possess electroreceptive organs in the head and thus presumably employ electroreception. Despite their vestigial nature, the eyes of White olms are not completely useless and are able to detect light. Olms appear to mostly prey on aquatic crustaceans but also eat snails and insect larvae. Captive specimens have eaten worms and adults may be cannibalistic on occasion. When I visited Postojina we were told that the olms on display were not fed both because their food proved hard to procure, and because they were quite able to survive for years without feeding. Indeed there was apparently a specimen kept at the Faculty of Biotechnology in Ljubljana which survived for an astonishing 12 years without food. Olms are long-lived, reaching sexual maturity between 7 and 14 years, and almost certainly ordinarily live for more than 50 years, though ages twice this have been suggested by some writers.

PS - for the latest news on Tetrapod Zoology do go here.

The photo above is from here.

Refs - -

Chippindale, P. T., Bonett, R. M., Baldwin, A. S. & Wiens, J. J. 2004. Phylogenetic evidence for a major reversal of life-history evolution in plethodontid salamanders. Evolution 58, 2809-2822.

Fitzinger, L. 1850. Ueber den Proteus anguinus der Autoren. Sitz.-Ber. Akad. Wiss., Math.-naturw. Cl. 5, 291-303.

Griffiths, R. A. 1996. Newts and Salamanders of Europe. T & A D Poyser (London).

Hanken, J. 1999. Why are there so many new amphibian species when amphibians are declining? Trends in Ecology & Evolution 14, 7-8.

Keeling, C. 2004. Olm. Mainly About Animals July 2004, 20-21.

Laňka, V. & Vít, Z. 1985. Amphibians and Reptiles. Hamlyn (London).

Laurenti, J. L. 1768. Specimen Medicum Exhibens Synopsis Reptilium Emendatum. Joan. Thomae (Vienna).

Min, M. S., Yang, S. Y., Bonett, R. M., Vieites, D. R., Brandon, R. A. & Wake, D. B. 2005. Discovery of the first Asian plethodontid salamander. Nature 435, 87-90.

Mueller, R. L., Macey, J. R., Jaekel, M., Wake, D. B. & Boore, J. L. 2004. Morphological homoplasy, life history evolution, and historical biogeography of plethodontid salamanders inferred from complete mitochondrial genomes. Proceedings of the National Academy of Sciences 101, 13820-13825.

Parra-Olea, G. & Wake, D. B. 2001. Extreme morphological and ecological homoplasy in tropical salamanders. Proceedings of the National Academy of Sciences 98, 7888-7891.

Scopoli, J. A. 1772. Annus Quintus Historico-Naturalis. C. G. Hilscher (Lipsiae).

Sket, B. 1997. Distribution of Proteus (Amphibia: Urodela: Proteidae) and its possible explanation. Journal of Biogeography 24, 263-280.

- . & Arntzen, J. W. 1994. A black, non-troglomorphic amphibian from the karst of Slovenia: Proteus anguinus parkelj n. ssp. (Urodela: Proteidae). Bijdr. Dierk. 64, 33-53.

Valvasor, J. W. 1689. Die Ehre des Herzogthums Crain. W. M. Endtner (Nuernberg).