Biggest sauropod ever (part…. II)

In the previous post we looked at the obscure and poorly known mega-sauropod Amphicoelias fragillimus, described in 1878 on the basis of an incomplete but enormous dorsal vertebra and the distal end of a femur. Its details show that it was a diplodocoid, and thus related to more familiar taxa like Diplodocus and Apatosaurus. Despite its absurd size – suggesting (by comparison with other diplodocoids) a total length of 60 m – this material somehow vanished prior to 1921. Due in part to these facts (and also, perhaps, to its poorly publicised and unfamiliar-sounding – or ‘crappy’ – name), Amphicoelias fragillimus was to be all but forgotten in the decades that followed…

During the 1990s, little-known articles by John McIntosh (revered older statesman of sauropod research) and Greg Paul looked briefly at A. fragillimus. McIntosh (1998) went through Cope’s inventories of the Garden Park discoveries (these records had been missed by Henry Osborn and Charles Mook in their 1921 review of Cope’s sauropod collection) and found that, perhaps because the contents of several crates have no surviving records, the shipment of A. fragillimus to New York wasn’t recorded. Paul (1994a, b) estimated the size of A. fragillimus based on the dimensions provided by Cope, suggesting (again, based on comparison with more completely known diplodocoids) a total length of 40-60 m, a weight of 100-150 tons, and that it would have been 9 m tall at the hips, and with thighs 3.8 m long.

The news is that, at long last, a proper reappraisal of this mysterious giant has finally appeared: it’s a new paper by Ken Carpenter of the Denver Museum of Nature and Science, and while, sadly, it doesn’t report the discovery of a new, articulated A. fragillimus specimen, it does cover pretty much everything we know about this dinosaur (Carpenter 2006). By the way, Carpenter and colleagues have tried looking for additional remains of A. fragillimus, thus far without success. Actually, I have to note here the rumour that new A. fragillimus material has been discovered, and that it will be discussed at the 2008 Society of Vertebrate Paleontology meeting. We shall see [adjacent image is Cope’s original 1878 figure of the A. fragillimus vertebra. I ripped it off from Matt Celeskey’s post about A. fragillimus from August of last year (go here). Sorry Matt].

Was A. fragillimus a hoax?

Unsurprisingly, quite a few people have been sceptical about the existence of this all-too-conveniently lost mega-sauropod. Can we be sure that it ever really existed, or could it be that Cope was pulling a fast one in order to beat his rival, Othniel Charles Marsh, hands-down in an effort to describe the biggest sauropod? As attractive as this scenario might appear, hoaxing is highly, highly unlikely. Consider the following:-

-- Cope was very specific about all the discovery details of A. fragillimus. According to his field notes, it was collected in late 1877 by Oramel Lucas (described by Cope as his ‘indefatigable friend’) at Garden Park, specifically from quarry III, a site southwest of the hill known today as Cope’s Nipple (Carpenter 2006). The rocks here yielded several other particularly large Morrison Formation dinosaurs (such as Camarasaurus supremus).

-- Furthermore, the shipment records discovered by McIntosh show that Oramel Lucas and his brother Ira knew of A. fragillimus and labelled some remains with this name (McIntosh 1998, p. 487 and p. 498). If it was a hoax, then the Lucas brothers must have been in on it too, which now makes it a conspiracy.

-- The conspiracy would have to extend even further, as an American Museum of Natural History catalogue number, AMNH 5777, was reserved for the A. fragillimus material.

-- The rivalry that existed between Cope and Marsh is also relevant here (Marsh is pictured at left). As is well known, Marsh enjoyed making a very public fool of Cope when he made a technical error (Storrs 1994, Davidson 2002), and when he disagreed with Cope, or thought him wrong, Marsh was tediously pedantic in his criticisms (see Marsh’s 1873 papers on dinoceratans, for example). Marsh never criticised, nor even questioned, the reality of A. fragillimus. Carpenter (2006) notes that ‘Marsh is known to have employed spies to keep tabs on what Cope was collecting, and it is quite possible that he had independent confirmation for the immense size of A. fragillimus’ (p. 134).

-- Cope’s drawing of A. fragillimus is accurate-looking and elaborate, and his description refers to small detailed features, all of which conform in details with what we know of diplodocoid vertebrae (part of the description is reproduced at left: from here). He would have to have made all of this stuff up if the specimen was a hoax: it’s not as if the only record of A. fragillimus is a scribbled fragment in a diary, saying ‘On Tuesday I saw the biggest vertebra ever… it was thiiiiis big…’. Rather, the material is documented, in detail, in a proper technical paper. To hoax an entire paper of this sort would be severe science-crime, and there is no indication that Cope was unscrupulous or dastardly, or prepared to stoop this low.

-- It is noteworthy that workers well known for their methodical and conservative approach to sauropod studies (notably John McIntosh) have accepted Cope at his word. Osborn, who succeeded Cope as vertebrate palaeontologist for the US Geological Survey and is well known for speaking his mind when he had a problem with something, also never voiced doubts about A. fragillimus.

All of this is circumstantial, for sure, but I agree with Carpenter (and others) that the idea of Cope perpetrating a hoax of this magnitude is pretty much unthinkable. I think we have to assume that the specimens really existed. Therefore, they must have become lost or destroyed some time between 1878 and 1921 (when Osborn and Mook failed to find them). As Carpenter (2006) points out, it in fact appears likely that the material was too fragile to survive, and that it crumbled to bits some time after its discovery. Matt Celeskey also noted this possibility (go here). Cope commented on this fragility, writing ‘in the extreme tenuity of all its parts, this vertebra exceeds this type of those already described, so that much care was requisite to secure its preservation’ (p. 563), and his drawing also suggests that the vertebra had been subjected to extensive weathering and hence was already fragile. Indeed its fragile nature explains the specific name he chose for it.

Furthermore, ‘preservatives had not yet been employed to harden fossil bones, the first of which was a sodium silicate solution used in O. C. Marsh’s preparation lab at Yale University beginning in the early 1880s’ (Carpenter 2006, p. 134). Support for the hypothesis that the material simply did not survive collection and storage comes from the fact that, within recent years, a Camarasaurus supremus vertebra collected from the same area is known to have crumbled into small useless fragments.

The other Amphicoelias

As I’ve now mentioned a few times, the detailed anatomy of the A. fragillimus vertebra (as figured by Cope) shows us that this sauropod was a diplodocoid. We can make a confident statement like this because it is relatively easy to distinguish the different sauropod clades on the basis of their vertebral anatomy, and A. fragillimus has all the distinctive anatomical features typical of diplodocoids. In fact it strongly resembles the vertebrae of the first named species of Amphicoelias, A. altus, which Cope described in February 1878.

A. altus is poorly known, but not as poorly known as A. fragillimus: it was first described for vertebrae, a pubic bone and a femur (Cope 1878), but a scapula, coracoid, ulna and partial skull were later referred to it. Based on these remains, A. altus was similar in size to Diplodocus carnegii and probably around 25 m long (Paul 1994a, b), and it is particularly interesting among diplodocoids in that its femora were markedly elongate and slender. Some workers have regarded A. altus as particularly close to Diplodocus, in which case it would be a diplodocid diplodocoid, and probably a diplodocine diplodocid diplodocoid. However, it has also been asserted that A. altus was a basal diplodocoid, and thus more archaic than diplodocids and other flagellicaudatan diplodocoids (that’s right, I said flagellicaudatan) [adjacent image shows Diplodocus mount at Denver Museum of Nature and Science].

Was Cope right in referring his second Amphicoelias species to the same genus as the first? Several authors have thought so, and in fact have gone so far as to state that ‘it is doubtful … if the characters described by Cope warrant the placing of the type [of A. fragillimus] in another species different from A. altus’ (Osborn & Mook 1921, p. 279), or ‘there is no reason not to consider [A. fragillimus] a very large individual of A. altus’ (McIntosh 1998, p. 502). If this is true then, like A. altus, it’s reasonable to assume that A. fragillimus was also superficially Diplodocus-like, and with particularly elongate, slender femora (a shocking idea given the animal’s size).

Carpenter argues in his new paper that, in fact, A. fragillimus seems to have differed from A. altus in a number of anatomical details, and that the two might not have been congeneric after all. As he notes, this remains untestable in the absence of better remains however. Let’s all hope and pray that a new generic name is up for grabs, and I don’t want any ‘superlative + saurus’ nominations.

One final thing. What’s with the image at the top of the page? I discovered it while googling Amphicoelias. Huh, in my day the only decent zoid was Hellrunner... For the story on the image at left go here (no, that’s not an Amphicoelias vertebra, it’s Matt Wedel. The bone, however, is from a diplodocoid... although not an Amphicoelias), and for previous posts on sauropods see the series on ‘Angloposeidon’, the Christmas post on Turiasaurus, some assorted ramblings on British Wealden sauropods, and a post devoted entirely to the anatomy of their hands.

Refs - -

Carpenter, K. 2006. Biggest of the big: a critical re-evaluation of the mega-sauropod Amphicoelias fragillimus Cope, 1878. New Mexico Museum of Natural History and Science, Bulletin 36, 131-137.

Cope, E. D. 1878. On the saurians recently discovered in the Dakota Beds of Colorado. The American Naturalist 12 (2), 71-85.

Davidson, J. P. 2002. Bonehead mistakes: the backround in scientific literature and illustrations for Edward Drinker Cope’s first restoration of Elasmosaurus platyurus. Proceedings of the Academy of Natural Sciences of Philadelphia 152, 215-240.

McIntosh, J. S. 1998. New information about the Cope collection of sauropods from Garden Park, Colorado. Modern Geology 23, 481-506.

Osborn, H. F. & Mook, C. C. 1921. Camarasaurus, Amphicoelias and other sauropods of Cope. Memoirs of the American Museum of Natural History, n.s. 3, 247-287.

Paul, G. S. 1994a. Big sauropods – really, really big sauropods. The Dinosaur Report Fall 1994, 12-13.

- . 1994b. Is Garden Park home to the world’s largest known land animal? Tracks in Time 4 (5), 1.

Storrs, G. W. 1984. Elasmosaurus platyurus and a page from the Cope-Marsh war. Discovery 17 (2), 25-27.

Biggest…. sauropod…. ever (part…. I)

Finally, it’s that post on gigantic mega-sauropods you’ve all been oh-so-patiently waiting for. Note that I’ve decided to do a new thing, and have left the ‘teaser post’ on its own (rather than over-writing it with this new version). Talking of new things, recall that something about my blogging habits is set to change soon.. the word is already on the street (to use the words of Carel Brest van Kempen), but I’m going to keep quiet about it for a bit longer. All will be revealed [UPDATE: go here for the news]. Anyway, to business. Even if you’re not an expert on dinosaurs, it’s likely that you’ve heard – firstly – that some sauropods were rily, rily big and – secondly – that these biggest of the big included such whoppers as Seismosaurus, Supersaurus and Argentinosaurus. It’s always helpful that their names are easy to remember. Recent work has not only resulted in the publication of reasonably accurate size estimates for these dinosaurs, it has also clarified their taxonomy and phylogenetic positions.

Supersaurus vivianae from the Morrison Formation of Colorado is, despite its name, a valid taxon – specifically it’s a diplodocid diplodocoid, and apparently an apatosaurine (the image at the top of page shows a new skeletal mount of this taxon). Recent estimates put its total length at 33 m. The most oft-figured bit of Supersaurus is its immense scapulocoracoid: it’s usually depicted with the late Jim Jensen, its discoverer and describer, lying alongside it. For a change, here (at left) is a curious new take on the theme (borrowed from here). Oh, and if you’re wondering about Ultrasauros (originally informally named Ultrasaurus: note the spelling difference), it’s no longer regarded as a valid taxon: the type material - a dorsal vertebra - was shown by Brian Curtice and colleagues (Curtice et al. 1996) to belong to Supersaurus (come back Brian, all is forgiven!) while the famous Ultrasauros scapulocoracoid seems to belong to Brachiosaurus. Below, at left, you can see dead fish expert Graeme Elliott standing alongside the Ultrasauros scapulocoracoid (go here for hilarious caption, sorry Graeme).

Moving on, Seismosaurus hallorum (originally described as S. halli), from the Morrison Formation of New Mexico, is also a diplodocid diplodocoid, but recent work indicates that it is not generically distinct from Diplodocus and should thus be renamed Diplodocus hallorum. Originally claimed to be over 40 m long, new estimates put it between 30 and 35 m. Supersaurus and Diplodocus hallorum, being relatively gracile diplodocids, probably weighed between 25 and 50 tons (Paul 1994a, b, 1997).

A few more super-sauropods have been added to the list in recent years. Most are titanosaurs, the predominantly Cretaceous sauropod clade originally thought to be late-surviving relatives of diplodocoids but now known to be close kin of the short-skulled camarasaurs and brachiosaurs. Argentinosaurus huinculensis, named in 1993, is a huge titanosaur from the Upper Cretaceous Río Limay Formation of Argentina: it was perhaps 30 m long. Paralititan stromeri is another massive titanosaur, this time from the Upper Cretaceous of Egypt. Estimated by its describers as having been around 30 m long, it has more recently been down-sized to a mere 26 m (image below left is Todd Marshall’s painting of Paralititan, taken from here. Go here for yours truly posing in bizarre fashion with the same image). Puertasaurus reuili, named in 2005 and from the Upper Cretaceous Pari Aike Formation of Argentina, was similar in size to these forms. Finally, Turiasaurus riodevensis is a gigantic Spanish form, and it’s not a titanosaur, belonging instead to a hitherto unrecognised clade termed Turiasauria. It was described at the end of 2006 (go here for more) and is one of the biggest sauropods known, with a length of 36-39 m.

Exactly how heavy these mega-sauropods were is mildly controversial. Accurate mass estimates generally agree that they were on the order of 80-90 tons, but Royo-Torres et al. (2006), the describers of Turiasaurus, put this animal at half this. However, they used a notoriously unreliable method of estimating weight.

While you might have heard of Supersaurus, Seimosaurus or Argentinosaurus – and perhaps even Turiasaurus and Paralititan – have you heard of… Amphicoelias fragillimus? Well, ok, if you’re a dinosaur ubernerd then the answer will be yes, but not if you’re a normal person. Though described as long ago as 1878, this sauropod has remained decidedly obscure and hardly heard of until pretty recently. I’ve done my part for the cause, having mentioned it at every opportunity: in both Dinosaurs of the Isle of Wight, and Walking With Dinosaurs: The Evidence, it’s discussed and touted as, possibly, the biggest sauropod of them all. Naish & Martill (2001), for example, stated ‘What has recently been claimed as the biggest of all sauropods and, indeed, the biggest of all land animals, is actually a specimen discovered in 1878. Based only on a single enormous vertebra, now lost, Amphicoelias fragillimus has been estimated to have reached a length of 60 m and may have attained a weight of 150 tons!’ (p. 230). If these estimates are valid, then this animal was twice as long as Supersaurus and Diplodocus, and perhaps over four times heavier. Err, gosh.

Amphicoelias fragillimus, giant of giants

In August 1878 the famous and prolific scientist* Edward Drinker Cope (1840-1897), portrait at left, described a new immense sauropod, Amphicoelias fragillimus, from the Garden Park quarries of the Morrison Formation of Colorado. It was represented only by an incomplete dorsal vertebra and the distal end of a femur (contra Naish & Martill above: whoops!). A good drawing of the vertebra was provided (Cope 1878), showing that this sauropod was clearly a diplodocoid: a member of the same sauropod clade as Diplodocus, Apatosaurus and their relatives (the name Diplodocimorpha is also sometimes used for these animals: see Taylor & Naish 2005: free pdf available here). The big deal is how, err, big these remains were. The partial vertebra had a preserved height of 1.5 m and, when reconstructed on the basis of comparison with complete diplodocoid vertebrae, has a total height of 2.7 m. Again… gosh (or words to that effect).

* Though usually described (by palaeontologists) as a palaeontologist, Cope was also an accomplished herpetologist and ichthyologist, which explains the name of the journal Copeia.

If history were fair, we would all have grown up familiar with Cope’s hyper-enormous Amphicoelias fragillimus, and we would be less impressed by Brachiosaurus and Balaenoptera, let alone with paltry little 20-m long sauropods like ‘Angloposeidon’ (go here). But it was not to be, and it was to sink into the morass of obscurity. In a major 1921 review of Cope’s sauropods, Henry Fairfield Osborn and Charles Mook noted that they were unable to locate the immense vertebra in Cope’s sauropod collection (Osborn & Mook 1921), today at the American Museum of Natural History (New York). It was lost.

And… I’ll have to stop there. The rest of the story will come in part II: I am aiming to post it tomorrow (10th Jan 2007). It concentrates on those recent studies that have looked at this species, and one of the most-asked questions about this remarkable dinosaur: was it a hoax? Stay tuned, all will be revealed. And I’m not stringing it out on purpose – I honestly don’t have enough time in my life to deal with all this stuff in one go. Sigh. And apologies to Ken Carpenter, who is no doubt wondering why I haven’t yet cited his paper…

Refs - -

Cope, E. D. 1878. A new species of Amphicoelias. American Naturalist 12, 563-565.

Curtice, B. D., Stadtman, K. L. & Curtice, L. J. 1996. A reassessment of Ultrasauros macintoshi (Jensen, 1985). In Morales, M. (ed) The Continental Jurassic. Museum of Northern Arizona Bulletin 60, 87-95.

Davidson, J. P. 2002. Bonehead mistakes: the backround in scientific literature and illustrations for Edward Drinker Cope's first restoration of Elasmosaurus platyurus. Proceedings of the Academy of Natural Sciences of Philadelphia 152, 215-240.

McIntosh, J. S. 1998. New information about the Cope collection of sauropods from Garden Park, Colorado. Modern Geology 23, 481-506.

Naish, D. & Martill, D. M. 2001. Saurischian dinosaurs 1: Sauropods. In Martill, D. M. & Naish, D. (eds) Dinosaurs of the Isle of Wight. The Palaeontological Association (London), pp. 185-241.

Osborn, H. F. & Mook, C. C. 1921. Camarasaurus, Amphicoelias and other sauropods of Cope. Memoirs of the American Museum of Natural History, n.s. 3, 247-287.

Paul, G. S. 1994a. Is Garden Park home to the world’s largest known land animal? Tracks in Time 4 (5), 1.

- . 1994b. Big sauropods – really, really big sauropods. The Dinosaur Report Fall 1994, 12-13.

- . 1997. Dinosaur models: the good, the bad, and using them to estimate the mass of dinosaurs. In Wolberg, D. L., Stump, E. & Rosenberg, G. D. (eds) Dinofest International: Proceedings of a Symposium Sponsored by Arizona State University. Academy of Natural Sciences (Philadelphia), pp. 129-154.

Royo-Torres, R., Cobos, A. & Alcalá, L. 2006. A giant European dinosaur and a new sauropod clade. Science 314, 1925-1927.

Taylor, M. P. & Naish, D. 2005. The phylogenetic taxonomy of Diplodocoidea (Dinosauria: Sauropoda). PaleoBios 25, 1-7.

Finally, some hot giant amphicoelian action

[click for larger version. Diagram produced by Ken Carpenter]

FULL POST TO COME LATER TODAY (9th Jan 2007)

After years of suffering all-too-brief mentions, asides and speculative remarks, the oft-alluded-to but long-neglected gigantic diplodocoid sauropod Amphicoelias fragillimus has been re-examined. Named by Edward Drinker Cope in 1878, it is known only from scant material (a single partial vertebra and fragment of femur) that – to make a bad situation worse – was somehow lost prior to the 1920s. But scant and lost or not, this material shows that A. fragillimus was immense, and in fact the most immense of all mega-sauropods. Full post to follow soon…

Thanks to Mike P. Taylor for the heads-up.

And for the latest news on Tetrapod Zoology do go here.

Happy Christmas, from gigantic Spanish sauropods... or, alas, poor ‘Angloposeidon’

I said the last post would likely be the last before 2007. I lied, as while checking my emails this morning, something came up that I just can’t resist commenting on. As regular blog-readers will know, back in 2004 I and colleagues described a large cervical vertebra from an Isle of Wight sauropod dinosaur (see ‘Angloposeidon’, the unreported story: part I, part II, part III and part IV). Belonging to a large brachiosaurid closely related to the Upper Jurassic Brachiosaurus and Lower Cretaceous Sauroposeidon, the Isle of Wight specimen is 745 mm long, which suggests a total length exceeding 20 m. That made it the largest published European dinosaur (Naish et al. 2004). However, when the time came to talk to journalists about the discovery, I mentioned on several occasions the fact that even bigger European dinosaurs were due to the published in the near future. As I said in part IV…

During the long period of time in which the [‘Angloposeidon’] manuscript was in preparation I spoke to several European colleagues who told me of new sauropods from Portugal and Spain that would easily outclass MIWG.7306 in terms of size. I had this on my mind all the way through the submission process, and at any time I expected there to be some report of a new European sauropod that had a total length exceeding 30 m. But even today such discoveries have yet to materialise, and having now seen some of the specimens in question I know that they fail to come close to the 20 m + estimated for MIWG.7306.

The news, of course, is that one of these Iberian giants has just been published (Royo-Torres et al. 2006): it’s the new taxon Turiasaurus riodevensis from the Villar del Arzobispo Formation (Jurassic-Cretaceus boundary) of Riodeva (Teruel Province, Spain) [many thanks to those who have sent the pdf!]. And it doesn’t fail to meet the hype: it really is immense (so, the other Iberian giants that I’ve seen were mere pretenders). Turiasaurus has a humerus about 1.8 m long and an estimated weight of over 40 tons. This makes it quite bigger than ‘Angloposeidon’ and in fact one of the biggest sauropods in the world, almost on par with immense titanosaurs like Argentinosaurus and Paralititan. Furthermore, phylogenetic analysis indicates that Turiasaurus belongs to a new clade located close to the origin of Neosauropoda (the macronarian-diplodocoid clade). Galveosaurus (named in 2005, and previously regarded as a cetiosaurid*) and Losillasaurus (named in 2001 and regarded as a diplodocoid, but since suggested to be a mamenchisaurid**) also seem to be turiasaurians. That’s pretty interesting, though it has to be said that the statistical support for turiasaurian monophyly is not overwhelmingly impressive.

* And later renamed Galvesaurus by a different group of authors. I will cover the Galveosaurus-Galvesaurus issue some time in the future.

** The correct term for the group dubbed ‘omeisaurids’ by some.


Furthermore, the fact that Turiasaurus is represented by good, associated remains means that it might help clear up some of the mess represented by isolated remains (see previous post: Obscure dinosaurs of the Kimmeridge Clay). Scattered throughout the European Jurassic and Cretaceous record are assorted sauropod teeth that roughly resemble the teeth of better known forms, such as camarasaurs and brachiosaurids, but also have a unique look about them. Examples include the huge, beautifully preserved tooth named Oplosaurus armatus (from the Isle of Wight*) and the unusual specimen Cardiodon rugulosus from the Middle Jurassic Forest Marble Formation of Bradford-on-Avon, Wiltshire. It now turns out that these teeth are similar to those of Turiasaurus, which raises the interesting possibility that they are further representatives of this newly-recognised group. That would be cool.

* For more on Oplosaurus and other Lower Cretaceous English sauropods go here.

Anyway, I’ll have more to say on turiasaurians and other Iberian sauropods in the future. And it really is relevant as I and colleagues (Barbara Sánchez-Hernández and Mike Benton) currently have an article in press on dinosaurs (including sauropods) from the Villar del Arzobispo Formation. Maybe some of the material we have belongs to Turiasaurus? We’ll see...

Finally, in other dinosaur news, you’ll note from the big picture above that Tom Holtz’s big dinosaur encyclopedia is finally being advertised. I discussed it previously here.

All the best for Christmas and the New Year. My new year’s resolution? To finish writing all those blog posts I’ve been promising for the last year. Controversial mammals from Borneo, the passerine supertree, rhinogradentians, giant Australian feral cats, temnospondyls, more on tupuxuarids, agamas and sea snakes, the biggest slow worms, fake Chinese turtles, amphisbaenians, and loads more on sauropods, theropods, pneumaticity, flightless birds, bizarre pterosaurs, and giant eagles. And keep an eye on Tetrapod Zoology’s 1st Birthday... Goodbye 2006!

Refs - -

Naish, D., Martill, D. M., Cooper, D. & Stevens, K. A. 2004. Europe’s largest dinosaur? A giant brachiosaurid cervical vertebra from the Wessex Formation (Early Cretaceous) of southern England. Cretaceous Research 25, 787-795.

Royo-Torres, R., Cobos, A. & Alcala, L. 2006. A giant European dinosaur and a new sauropod clade. Science 314, 1925-1927.

Obscure dinosaurs of the Kimmeridge Clay

Someone – I forget who it was – once described dinosaurs as ‘the most American animals that ever lived’. Well, with all due respect to North America’s endemic dinosaurs (Tyrannosaurus, Triceratops and so on), and to the worthy history of North American palaeontological discoveries, this is crap. Dinosaurs are no more American than they are Patagonian, Nigerian or French. Or at least that’s the politically correct version. Reality is rather different: dinosaurs are in fact British, and – what’s more – specifically English, having been discovered in England by English scientists working on English fossils. Ok, lest some flag-waving patriot of any nation gets offended by this, let me assure you that this is all tongue-in-cheek and not to be taken seriously. Dinosaurs no more ‘belong’ to any country than do rodents or grasshoppers.

England has a rich dinosaur record, and many of the taxa first named from English rocks (e.g., Hypsilophodon, Cetiosaurus, Baryonyx) have proved globally important in terms of what they’ve told us about dinosaur evolution and diversity. Furthermore, these taxa and others (e.g., Scelidosaurus, Mantellisaurus, Neovenator) are represented by excellent remains that sometimes consist of near-complete skeletons. Also noteworthy is that English dinosaurs span most of the Mesozoic, from the Upper Triassic to about the middle of the Cretaceous (there is no dinosaur-bearing Upper Cretaceous in England). So as a gross generalisation of the worse kind, England’s dinosaur record is ‘good’.

Partly because the study of dinosaurs began in England, there is an extensive and voluminous literature on scrappy English dinosaur fossils. Furthermore, these early finds were usually given binomial names, but as our knowledge of these animals has improved, it is understandable that many of these remains are today considered inadequate in terms of establishing taxonomic validity. Ideas on British taxa were sometimes revised several or many times as knowledge improved, and the results are convoluted synonymy lists. As I’ve now mentioned several times on this blog, a major effort to review this mess has recently been produced by Dave Martill and myself, and is currently in press for a special bicentennial issue of Journal of the Geological Society. More on that when it appears. In an unrelated project, Dave, I and Sarah Fielding recently reviewed the English dinosaurs of the Kimmeridge Clay Formation, and as it’s only recently been published (Martill et al. 2006) I figured I may as well blog about it.

The Kimmeridge Clay

The Kimmeridge Clay Formation is an Upper Jurassic mudrock, deposited within a shallow marine environment, that crops out in a narrow strip from Dorset in the south-west to Yorkshire in the north-east. There are also a few outcrops in Scotland, and a contemporaneous equivalent that crops out in northern France. Like the older Oxford Clay Formation (go see Life in the Oxford Clay sea), the Kimmeridge Clay has yielded numerous ichthyosaurs, plesiosaurs, marine crocodyliforms and fish. Excepting the fish of course, those animals are all very interesting and worthy of discussion, but of more interest right now are the many dinosaurs that have also been discovered in the Kimmeridge Clay.

Why have so many dinosaurs been recovered from a geological unit deposited in a shallow sea? Despite the title of our paper, I don’t think this means much. The dinosaurs we find in these marine rocks don’t exhibit any features suggesting that they were aquatic or amphibious, and it appears most likely that the carcasses of the relevant species were washed out to sea on a fairly regular basis. This is well supported by the fact that other fossils, such as plants, and the sediments themselves, have clearly been derived from terrestrial sources. At a time when shallow seas covered the better part of the European continent, it makes sense that an unusually high number of terrestrial animals living on the archipelagos of the region found their way into the marine environment.

Kimmeridge Clay dinosaurs belong to most of the major groups living in Europe during the Upper Jurassic. There were large and small theropods, several types of sauropod, herbivorous ornithopods, and both stegosaurs and ankylosaurs.

Kimmeridge Clay sauropods

Perhaps the most interesting of the Kimmeridge Clay sauropods was named by John Whittaker Hulke* in 1874. Based only on a big humerus (1.3 m long, though perhaps 1.7 m long when complete: see adjacent image) discovered at Weymouth, Hulke named it Ceteosaurus humero-cristatus: note that he used a spelling of the generic name that later fell out of favour (the original, and thus favoured, spelling is Cetiosaurus), and used a hyphen in the specific name (an action that is illegal under today’s nomenclatural rules). This animal is quite certainly not really a species of Cetiosaurus (hence the quote marks used from hereon), as it is highly different in detail from the humerus of Cetiosaurus oxoniensis, the type species of the genus (well, actually, C. oxoniensis is not yet the type species of the genus, but that’s a long and complex issue that I can’t go into right now). So what is it? Its length, slender proportions and particularly prominent deltopectoral crest show that it is a brachiosaurid and, among brachiosaurids, its particularly long deltopectoral crest makes it unique and diagnosable. ‘C.’ humerocristatus is therefore one of those annoying fossil tetrapods that clearly needs a new name. So why doesn’t it have one?

The problem is that most workers who encounter problems like this prefer to err on the side of hyper-conservatism (Peter Dodson’s advice is that ‘the practise of naming genera on [the basis of isolated remains] is a highly undesirable one, greatly to be discouraged’ (Dodson 1996, p. 240): for more on this subject see Cryptic dinosaur diversity). Some therefore opt not to name something that they themselves have said deserves a name. In their review of sauropod species referred to Cetiosaurus, Upchurch & Martin (2003) concluded that ‘C.’ humerocristatus ‘is regarded as a distinct taxon referable to the Brachiosauridae’ but went on to state that ‘[w]e prefer to wait for more complete material before proposing a new name for this taxon’ (p. 213). Similarly, Upchurch et al. (2004) regarded ‘C.’ humerocristatus as ‘a potentially distinct taxon … [but] it would be unsafe to erect a new generic name given the material available’ (p. 309). This perpetuates the cycle, and the taxon goes unnamed for even longer.

I’m equally as guilty of this as are Upchurch and Martin: in an earlier draft of the Kimmeridge Clay manuscript, my co-authors did actually come up with a new generic name for ‘C.’ humerocristatus (it has to be said, a pretty awful one), but I managed to get it removed. While I think it would be useful if this apparently diagnostic brachiosaur were named, I guess I’m bowing to peer pressure. Presumably, ‘C.’ humerocristatus was built much like better-known brachiosaurids (such as Brachiosaurus: adjacent image is Greg Paul’s old restoration of Brachiosaurus with Ceratosaurus and pterosaurs), but it was surely different in various of its details. A few additional bones have been suggested to belong to it, but there’s no way of knowing whether these really do belong to the same animal as the diagnostic humerus.

* One of the most prolific dinosaur workers in England during the latter half of the 19^th century, Hulke (1830-1895) was a renowned ophthalmologist and firm ally of Huxley. Elected Fellow of the Geological Society of London in 1868, he was President by 1887 and, later, Foreign Secretary. Hulke was elected to the Royal Society for his work on the retina and received the Wollaston Medal in 1887. Research on prehistoric reptiles was only his hobby, but he published multiple papers on them, with 25 appearing in the Quarterly Journal of the Geological Society of London alone.

Various other sauropod remains have been reported from the Kimmeridge Clay. ‘Ornithopsis’ manseli was named in 1888 for another isolated humerus, and again it appears to be from a brachiosaurid. In fact it might be the same animal as ‘C.’ humerocristatus. Yet again it was originally placed in an inappropriate genus: Ornithopsis is a Lower Cretaceous sauropod (first named for dorsal vertebrae), and there’s no reason at all to think that an Upper Jurassic humerus should be referred to a genus based on Cretaceous vertebrae.

Then there’s Bothriospondylus suffossus, based on vertebrae. Often regarded as a brachiosaurid, its remains are not diagnostic, nor is there any reason to think that they belong to a brachiosaurid, nor even to a macronarian (Macronaria is the sauropod clade that includes brachiosaurids and titanosaurs). Because Bothriospondylus was named early in the scientific discovery of sauropods (in 1875), it quickly became a sort of ‘waste-basket’ taxon to which sauropod remains from all over the world were referred. Thus, various Cretaceous sauropod remains from England, as well as remains from the Middle Jurassic of Madagascar and the Upper Jurassic of France, have been identified (erroneously) as Bothriospondylus. Incidentally, the specific name of the type species of this genus is conventionally spelt incorrectly, with it usually being written ‘suffosus’. On naming the species in 1875, Richard Owen used both double f and double s, but most authors seem to have missed this for some reason.

Kimmeridge Clay theropods

Only a few theropods (predatory dinosaurs) have been reported from the Kimmeridge Clay, and two of them are particularly interesting. The first is interesting because it’s both reasonably well represented (its remains include vertebrae from all parts of the column, pelvic and hind-limb elements), and something new. It’s some kind of peculiar, gracile tetanuran, and is due to be studied as part of a larger project on Jurassic theropods.

The second specimen is considerably less impressive, consisting only of two phalanges from the foot. Discovered at Fleet in Dorset, they are presently part of a private collection. What makes them particularly interesting is the fact that they’ve been identified as belong to an ornithomimid (Brokenshire & Clarke 1993): a theropod clade (often known as ostrich dinosaurs) otherwise restricted to the Cretaceous. If the identification is correct, the history of this group would be extended considerably. However, an identification this precise, given that the material consists only of worn, isolated toe bones, is problematic and there is little reason to think that it is correct. The bones do superficially resemble the toe bones of ornithomimids, but they superficially resemble the toe bones of many other theropods as well. Consequently they are better identified as Theropoda indet. (Martill et al. 2006).

That’ll do for now. Of course there are also the ornithischians: anachronistic ornithopods and pliosaur chew-toys. More on them in the near future. Remember to keep checking for new Christmas cards. Seasons greetings to all - I don’t think I’ll get the chance to do any blogging between now and the new year.

A pdf of Martill et al. (2006) is available should anyone want it (email me: eotyrannus at gmail dot com).

For the latest news on Tetrapod Zoology do go here.

Refs - -

Brokenshire, A. J. and Clarke, J. B. 1993. Important recently collected dinosaurian remains from the Lower Kimmeridge Clay at Weymouth. Proceedings of the Dorset Natural History and Archaeological Society 115, 177-178.

Dodson, P. 1996. The Horned Dinosaurs. Princeton University Press, Princeton, NJ.

Martill, D. M., Naish, D. & Earland, S. 2006. Dinosaurs in marine strata: evidence from the British Jurassic, including a review of the allochthonous vertebrate assemblage from the marine Kimmeridge Clay Formation (Upper Jurassic) of Great Britain. In Colectivo Arqueológico-Paleontológico Salense (ed) Actas de las III Jornadas sobre Dinosaurios y su Entorno. Salas de los Infantes (Burgos, España), pp. 47-83.

Upchurch, P., Barrett, P. M. & Dodson, P. 2004. Sauropoda. In Weishampel, D. B., Dodson, P. & Osmólska, H. (eds) The Dinosauria, Second Edition. University of California Press (Berkeley), pp. 259-322.

- . & Martin, J. 2003. The anatomy and taxonomy of Cetiosaurus (Saurischia, Sauropoda) from the Middle Jurassic of England. Journal of Vertebrate Paleontology 23, 208-231.

‘Angloposeidon’, the unreported story, part IV

This post follows on from the previous three (part I here, part II here, and part III here), and if you read to the end of part III you’ll know that I got as far as talking about the media attention that the Naish et al. (2004) paper received in late November 2004. As mentioned, I spoke to lots of journalists, and among them, one in particular had something very interesting to say. Unfortunately I forget his name, but I do recall that he was based on the Isle of Wight. His recollection was that the specimen had in fact been brought to the attention of the media before. Basing my conclusions on what happened with Eotyrannus, this is almost certainly correct.

Steve Hutt’s plan with Isle of Wight dinosaur discoveries (and you’ll recall from the previous posts that Steve was the first person other than Gavin Leng to become acquainted with MIWG.7306) has always been to get publicity both on the discovery of a specimen, and on the publication of the formal description. So Eotyrannus was in the newspapers as a new dinosaur discovery in 1998, and then again in 2001 when it was formally named and described (Hutt et al. 2001). Most of us hold off on talking to the press until our technical work has been published, but I’m not knocking Steve for his double-whammy approach, as the media are evidently interested enough to cover these stories twice.

So while I’ve never seen the relevant articles, it seems that MIWG.7306 was reported in the newspapers at the time of its discovery. It also turns out that a semi-technical report was published on the specimen, and to my annoyance I didn’t find out about this until recently. The article in question is by Jon Radley, well known for his excellent work on Wealden stratigraphy, and it includes two paragraphs on the specimen and a photo (Radley 1997, pp. 108-109). The relevant section reads (though with some typos corrected)…

A brachiosaurid sauropod vertebra from the Wessex Formation (Wealden Group, Lower Cretaceous) of Sudmoor Point

In the autumn of 1993 Mr. G. Leng discovered a large sauropod vertebra derived from a plant debris bed exposed in the cliff top approximately 1 km northwest of Chilton Chine (SZ 399825). Mr. Leng has generously donated this important specimen to the Museum of IW Geology (MIWG 7306) with the permission of the National Trust. The specimen is preserved in a large, well-cemented sideritic concretion and is consequently only partly crushed. Small quantities of pyrite occur in the bone material and appear to be quite stable.

The bone is 0.75 m long and now ranks as the largest sauropod vertebra in the museum collection. Mr. S. Hutt has identified it as a cervical (neck) vertebra of an adult brachiosaurid sauropod. It is deeply socketed and possesses large prezygapophyses and postzygapophyses. The nature of construction is extremely light with well developed networks of pleurocoels (air chambers). From its size, one can calculate that it came from an animal approximately 22 to 25 m in length. Most brachiosaurid remains discovered so far on the Island are of considerably smaller animals – Radley & Hutt (1993) provided outline details of a recent find. It is hoped that the vertebra will be on temporary display in the museum in the near future.

A few things make Jon’s article particularly interesting. The ‘autumn of 2003’ date he provides is different from the 2002 one I was provided by MIWG staff, and the 750 mm length he provides is of course accurate (and presumably so because it’s the centrum length alone). The article also includes the first ever figure of the specimen, showing it in its unprepared, siderite-encased case (a scan of that figure is included here). Of course the article doesn’t in any way diminish the value of the final published description (Naish et al. 2004) and is nothing more than an initial, preliminary report. I just wish that I’d known about it when writing Dinosaurs of the Isle of Wight and the final MIWG.7306 paper, as then I could have cited it. Oh well.

It turns out that the final published description – while not bad as descriptions go – only really scratches the surface in terms of what information we can learn from MIWG.7306. Previously I discussed the incredible fact that brachiosaurid vertebrae are as much as 80 or 90% air, and that this degree of pneumatisation might mean an awful lot as goes physiology and biology. Because MIWG.7306 is broken into halves, making examination of its pneumatic interior possible, a current project is to get lots more data about pneumaticity out of it. That’s ongoing however, so I don’t want to talk more about it now.

MIWG.7306 also gives us new information on the diversity and distribution of brachiosaurids. MIWG.7306 clearly shares a number of detailed features only with Brachiosaurus of the Late Jurassic of North America and eastern Africa, and with Sauroposeidon of the Early Cretaceous of the USA, and as discussed in the paper (Naish et al. 2004) it seems that MIWG.7306 might even be phylogenetically intermediate between these two forms. One of the big questions concerning brachiosaurids is which other sauropods are members of this clade too, and this is an area currently under study by my colleague Mike P. Taylor, who has a lot of new data (and some new species) on this subject.

But if MIWG.7306 represents an animal that is ‘phylogenetically intermediate’ between Brachiosaurus and Sauroposeidon, and given that it’s been publicised as a ‘new’ dinosaur, why didn’t we name it? That’s a good question, and there are two answers.

Firstly, most experts agree that specimens should only be named as new taxa if they can be can be shown to be diagnostic: that is, they possess unique features which allow them to be differentiated from other taxa. Given that taxa evolve from ancestors, and evolve into descendants, there aren’t sharp boundaries between species and genera – rather, they grade into one another. Consequently, so-called diagnostic features must also, at some stage in any lineage, morph into the slightly different conditions present in ancestors and/or descendants, and multiple intermediate conditions must exist between any two ‘diagnostic’ end-states. We therefore, arbitrarily, chose cut-off points in how much variation we tolerate within any taxon – in other words, we arbitrarily decide how we chop up a lineage into those units we call species and genera. As a rough rule of thumb this all works, more or less, so long as it’s understood that species are artificial segments of lineages (though having said that, any species that can be shown to be the ‘end point’ of its respective lineage is a clade, and of course this applies to living species given that they don’t have descendants). Anyway, I’m going off here at a tangent: this is the sort of heavy philosophical stuff that systematists have been arguing over for decades.

MIWG.7306 possesses loads of anatomical features that are also present in Brachiosaurus and Sauroposeidon, and it even shares some features that are present in Sauroposeidon and not in Brachiosaurus but, so far as we can tell, it doesn’t possess any features that are unique and thereby allow it to be reliably differentiated from all other sauropods. That’s almost certainly is an artefact resulting from the fact that we only have two cervical vertebrae of course – if we had the whole skeleton things would be different. But, as it stands, MIWG.7306 cannot presently be diagnosed as a new species.

Actually, for a while I’ll admit that we thought that MIWG.7306 could be diagnosed. One of several unsolved mysteries about the specimen is the identity of a bizarre, oddly shaped chunk of bone found encased in the same nodule (Dave Martill is holding it in the adjacent image). Smoothly convex on one side, but with a series of subparallel ribs on the other, it was tentatively identified by David Cooper as part of the apex of the neural spine. I thought later on that it might be a partial diapophysis*, as those of brachiosaurids can descend ventrally from the side of the centrum as plate-like processes with smoothly convex lateral surfaces. If this identification is right, then the diapophysis of MIWG.7306 is uniquely odd, as it possesses a small rhomboidal opening near its (presumed) posterior border. Such a feature is unknown elsewhere in sauropods, and it’s the sort of feature we might chose to regard as diagnostic. I now have serious doubts about my identification of this object as a diapophysis, and I think that David was right with the neural spine identification. Images of the object were shown to sauropod-obsessed colleagues, and they remains uncertain as to what it is however, so the thing remains mysterious.

* In tetrapods with two-headed ribs, the more ventral rib head contacts a facet on the vertebra known as the parapophysis (plural parapophyses), while the more dorsal rib head contacts a facet known as the diapophysis (plural diapophyses). The positions of the parapophyses and diapophyses change along the length of the vertebral column, and indeed their relative positions allow us to identify where in the sequence an isolated vertebrae came from.

The second answer [to the question: why didn’t we name it?] is that MIWG.7306 comes from a geological unit (the Wessex Formation) where there are already lots of named sauropods, virtually all of which are based on non-overlapping fragments, such as vertebrae. What’s more, some of these (notably Eucamerotus, a form named for dorsal vertebrae), seem to be good honest brachiosaurids closely related to Brachiosaurus (and hence to MIWG.7306). It’s possible and perhaps likely that some of the other Wessex Formation sauropods, Eucamerotus among them, actually represent the same taxon as MIWG.7306, though of course this can’t be tested until we have good, more complete specimens (here you’ll recall the Barnes High brachiosaurid, still floating in scientific limbo). In view of this situation it would be regarded as bad practise to coin a new name for MIWG.7306.

Partly because it’s easier to say than ‘MIWG.7306’ we’ve elected to use a totally unofficial nickname for the taxon represented by MIWG.7306, and this is ‘Angloposeidon’, coined by brachiosaurophile Mike P. Taylor (who is irritated by my continual reference to him as such*). So long as it stays on the internet we’re ok: it must NOT be published!

* So why do I do it? Because there is already a well known Mike Taylor in the world of tetrapod zoology: the marine reptile expert Mike A. Taylor.

What do other experts think of MIWG.7306? During the long period of time in which the manuscript was in preparation I spoke to several European colleagues who told me of new sauropods from Portugal and Spain that would easily outclass MIWG.7306 in terms of size. I had this on my mind all the way through the submission process, and at any time I expected there to be some report of a new European sauropod that had a total length exceeding 30 m. But even today such discoveries have yet to materialise, and having now seen some of the specimens in question I know that they fail to come close to the 20 m + estimated for MIWG.7306. The accompanying image – a composite produced by Matt Wedel and Mike – shows the forelimb of one of these ‘gigantic’ European sauropods (with me for scale) adjacent to the Chicago mount of Brachiosaurus (with Mike for scale). ‘Angloposeidon’ was about equivalent in size to Brachiosaurus so far as we know, and as you can see, Brachiosaurus knocks spots off the European animal (which, by the way, is as yet undescribed and unnamed).

The MIWG.7306 paper hasn’t been cited much in the literature, but this results from the fact that bugger all has been published on Lower Cretaceous British sauropods since 2004. Matt Wedel – pneumaticity and giant brachiosaurid expert – has certainly been interested and even came to see the specimen in March 2004. He’s agreed with our interpretations, and in recent publications on Sauroposeidon has noted that MIWG.7306 shows that Britain was once home to a close relative of this Oklahoman giant (Wedel 2005: free pdf here). Sauroposeidon is from the Aptian-Albian Antlers Formation, whereas the Wessex Formation that yields MIWG.7306 is just a little older, being late Barremian in age. We also know that similar giant brachiosaurids were present in the Aptian-Albian Cloverley Formation of Montana, as evidenced by a single cervical vertebra held today at the Yale Peabody Museum. The specimen is from a juvenile brachiosaurid but, as Wedel (2005) noted, at 47 cm in length the specimen ‘is longer than the vertebrae of many adult sauropods’ (p. 55). Footprints produced by Sauroposeidon, or by a similar, closely related brachiosaurid are known from the Glen Rose Limestone of the Paluxy River, Texas. At up a metre in diameter, they must have been produced by a real giant, and, among roughly contemporaneous North American sauropods, only Sauroposeidon is big enough (Wedel 2005).

And that’s pretty much the whole story up to now. The main message I suppose you should take away is that producing a technical paper on a specimen – even a short one devoted to the description of a single bone – can be an absurdly drawn-out, lengthy affair literally years in the making, and this is all the more so when other projects and life in general get in the way. Discovered by an enthusiastic amateur who donated the specimen to his local museum (Gavin Leng), prepared by an amateur with scientific training (David Cooper), and eventually described technically by a team of palaeontologists, the MIWG.7306 story is also a nice example of the sort of successful collaboration that can result if people work together.

However, there is also a sad ending to this story. David Cooper, who devoted so much time to the specimen and initiated the research that culminated in the paper, had been suffering for some time from cancer, and by 2005 he knew his condition was terminal. Late in June 2005 I received an unexpected and saddening phonecall. Given that I received this news the day before his funeral, I was unable at such short notice to make the arrangements to attend. This, I regret.

For the latest news on Tetrapod Zoology please go here.

Refs - -

Hutt, S., Naish, D., Martill, D. M., Barker, M. J. & Newbery, P. 2001. A preliminary account of a new tyrannosauroid theropod from the Wessex Formation (Early Cretaceous) of southern England. Cretaceous Research 22, 227-242.

Naish, D., Martill, D. M., Cooper, D. & Stevens, K. A. 2004. Europe’s largest dinosaur? A giant brachiosaurid cervical vertebra from the Wessex Formation (Early Cretaceous) of southern England. Cretaceous Research 25, 787-795.

Radley, J. 1997. Geological report 1993-1994. Proceedings of the Isle of Wight Natural History and Archaeology Society 13, 107-114.

Wedel, M. J. & Cifelli, R.L. 2005. Sauroposeidon: Oklahoma’s native giant. Oklahoma Geology Notes 65, 40-57.

Lots of sauropods, or just a few sauropods, or lots of sauropods?

I have a window of about 30 minutes before I need to get back to the British dinosaurs manuscript (which really needs to be finished by next week), so let’s see if I can get this done. As discussed in the previous blog entry, early last week Mike Taylor (see accompanying hilarious photo) and I spent the better part of a day working on Wealden sauropods in the Natural History Museum collections. The main point of this excursion was to have our final look (‘final’ as in last look before we submit our paper) at a specimen that we’ve been working on: a highly unusual, in fact deeply weird, new taxon collected in the late 1800s from the Ashdown Beds Formation (Valanginian) near Hastings. I won’t be saying more about it until it’s published, but its ‘discovery’ has prompted me to revisit the problematic area of Wealden sauropod diversity. Well, ok, I’m ‘revisiting’ that area anyway right now, what with the British dinosaurs manuscript, but still. Was sauropod diversity in the Early Cretaceous of England high, or low?

First things first: it’s misleading to think of the ‘Wealden’ as a short chunk of time, as this term actually applies to three formal stratigraphic groups (the Berriasian-Barremian Hastings Beds and Weald Clay Group of the mainland, and the Hauterivian-Aptian Wealden Group of the Isle of Wight). ‘Berriasian to Aptian’ is something like 30 million years, so that’s a lot of time for a whole lot of species to come and go. Whole assemblages of species in fact. Certainly the animals known from the Hastings Beds Group are not the same as those of the Barremian Wessex Formation (the best known dinosaur-bearing unit in the Wealden Group). The Hastings Beds Group has yielded Pelorosaurus conybeari (which is actually the same thing as Cetiosaurus brevis, but we won’t go there right now) and P. becklesii (which clearly isn’t congeneric with P. conybeari). P. conybeari, based on caudal vertebrae, chevrons and a large and gracile humerus, is a basal titanosauriform, perhaps a brachiosaurid. P. becklesii, named for tremendously short and robust forelimb elements and skin, is clearly a titanosaur. This is significant as it’s among the oldest of verified body fossil representing this clade. However, there are trackways that appear to have been produced by titanosaurs from the Bathonian of Ardley, Oxfordshire (Day et al. 2002, 2004), so titanosaurs had been around since the Middle Jurassic at least.

That’s not all – the Hastings Beds Group has also yielded a single metacarpal which has been identified as belonging to a diplodocid: that’s right, not just a diplodocoid, but a diplodocid. Angela Milner initially made this identification, and more recently I’ve had it verified by Matt Bonnan (pers. comm. 2006). Then we have the new taxon that Mike and I are looking it. It doesn’t seem that any of these animals can be conspecific, so, we have: a basal titanosauriform (and possible brachiosaurid), a good titanosaur, a diplodocid, and a new taxon that isn’t any of these.

What about the Wessex Formation, where 30-odd Barremian dinosaur species are known? Naish & Martill (2001) and Naish (2005) thought that sauropod diversity here was quite high, with a possible camarasaurid (Chondrosteosaurus), a few brachiosaurids, a titanosaur (Iuticosaurus valdensis), and an unnamed diplodocoid (represented by a chevron as well as isolated teeth and other elements). This now seems erroneous, or perhaps over-optimistic. The characters supposedly indicating camarasaurid status for Chondrosteosaurus are rubbish, and it’s more likely a basal titanosauriform (and it’s non-diagnostic anyway). The supposed diplodocoid bits are controversial, and the ‘sled-like’ morphology initially used to support a diplodocoid identity for the famous chevron (Charig 1980) is now thought to have been primitive for neosauropods, rather than derived for diplodocoids (see Upchurch 1998). It’s also difficult to be sure that there’s more than one brachiosaurid. The evidence for titanosaurs (procoelous caudal vertebrae, with a distinctively located neural arch) is reasonable, but the remains aren’t diagnostic.

Accordingly, when Paul Upchurch spoke about Wessex Formation sauropod diversity at the British dinosaurs Palaeontological Association Review Seminar in November 2003 (co-hosted by Dinosaur Isle Museum and the University of Portsmouth) he cautioned that diversity might have been over-estimated, and that titanosauriforms accounted for what diversity there was.

But while some groups – like camarasaurids – have now been removed from the list of taxa, new ones have been added (as it happens, camarasaurids were apparently present elsewhere in Lower Cretaceous Europe, but more about that another time). Firstly, there are definitely brachiosaurids present in the Wessex Formation: the big MIWG 7306 cervical vertebra that I and colleagues described in 2004 (Naish et al. 2004) is clearly more like the vertebrae of Brachiosaurus and Sauroposeidon than anything else (go here for more), and some of the dorsal vertebrae referred by Blows (1995) to his problematic taxon Eucamerotus foxi are also clearly brachiosaurid in the strict sense. Then there are the clearly titanosaurian caudal vertebrae, such as those described by Le Loeuff (1993). But there’s more.

A big and highly distinctive, pristine tooth forms the holotype of Oplosaurus armatus. Naish & Martill (2001), the idiots, thought that this might be another brachiosaurid, but that’s clearly wrong: Canudo et al. (2002) suggested that Oplosaurus might instead have been closer to Camarasaurus, and Upchurch et al. (2004) regarded it as a distinct neosauropod of uncertain affinities. Then there are the brachiosaurid teeth named Pleurocoelus valdensis: most authors have regarded these as non-diagnostic bits of brachiosaurid, but Ruiz-Omeñaca & Canudo (2005) have argued that they’re diagnostic and really represent a good species. Whatever they are, they’re clearly something else from Oplosaurus.

And then, finally, there are the diplodocoid teeth figured by Naish & Martill (2001) and identified by Wilson & Sereno as…. rebbachisaurid teeth! I can’t provide the citation for the latter as I don’t yet have the paper, but the recognition of these teeth as rebbachisaurid verifies the presence of diplodocoids in the Wessex Formation. Ok, so they aren’t diplodocid-like forms as Charig and others thought when they were looking at the chevron, but they’re diplodocoids nonetheless. In some senses this discovery isn’t a surprise as rebbachisaurids have lately been reported from Barremian-Aptian Spain (Fernández-Baldor et al. 2001, Pereda Suberbiola et al. 2003), but it now means that the oldest rebbachisaurids in the world are from England. Huh, so much for this being an exclusively Gondwanan clade.

So, in the Wessex Formation we have… an unusual neosauropod of uncertain affinities (Oplosaurus), definite brachiosaurids, definite titanosaurs, and a rebbachisaurid. That’s not bad in terms of diversity (adjacent picture shows diplodocoid and titanosaur). To remind you, in the older Hastings Beds Group we have a basal titanosauriform (and possible brachiosaurid), a titanosaur, a diplodocid, and a new and unusual taxon that isn’t any of these. So, also, not bad in terms of diversity, and in fact not that different from the Wessex Formation roster, which implies stability from the point of view of long-term diversity.

And, it’s on that point that I must get back to work. I was going to talk about the theropods, but that can wait.

Ref - -

Blows, W. T. 1995. The Early Cretaceous sauropod dinosaurs Ornithopsis and Eucamerotus from the Isle of Wight, England. Palaeontology 38,187-197.

Canudo, J. I., Ruiz-Omeñaca, J. I., Barco, J. L. & Royo Torres, R. 2002. ¿Saurópodos asiáticos en el Barremiense inferior (Cretácico Inferior) de España? Ameghiniana 39, 443-452.

Charig, A. J. 1980. A diplodocid sauropod from the Lower Cretaceous of England. In Jacobs, L. L. (ed.) Aspects of Vertebrate History, Essays in honour of E. H. Colbert. Museum of Northern Arizona Press, pp. 231-244.

Day, J. J., Norman, D. B., Gale, A. S., Upchurch, P. & Powell, H. P. 2004. A Middle Jurassic dinosaur trackway site from Oxfordshire, UK. Palaeontology 47, 319-348.

- ., Upchurch, P., Norman, D. B., Gale, A. S. & Powell, H. P. 2002. Sauropod trackways, evolution, and behavior. Science 296, 1659.

Fernández-Baldor, T., Pereda Suberiola, X., Huerta Hutado, P., Izquierdo, L. A., Montero, D. & Pérez, G. 2001. Descripción preliminar de un dinosaurio rebaquisáurido (Sauropoda Diplodocoidea) del Cretácico Inferior de Burgos (España). II Jornadas de Paleontología de Dinosaurios y su Entorno. Salasa de los Infantes (Burgos, España), 203-211.

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