Tetrapod Zoology

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Among one of many interesting and perplexing Mesozoic fossil assemblages is that known from Cornet, Romania. I’ve been really interested in this collection of archosaur remains – currently housed at the Tarii Crisurilor Museum, Oradea – ever since I first heard about it in the 1990s, and recently I’ve been lucky enough to work with Gareth Dyke, Michael Benton and Erika Posmosanu in re-evaluating the more controversial of the Cornet fossils: namely, those claimed to represent a bizarre and motley assortment of Mesozoic birds and pterosaurs. Our paper on these fossils has just been published in Palaeontology (Dyke et al. 2010). What do we say, and which animals are really present at Cornet? [for the full story on the cartoony image used below, you have to wait a few days. Drawing by Naish, colouring by Tim Morris].

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Discovered by chance after a mine explosion in 1978, the Cornet site (a former bauxite mine in Oradea, north-west Romania) has yielded hundreds of bones excavated over a period of 15 years (the mine flooded in 1999, so further excavation isn’t possible). Numerous papers have been published on the Cornet remains since 1978: some of these describe the relatively large bones of ornithopod dinosaurs (e.g., Benton et al. 1997, Posmosanu & Cook 2000)*, and remains possibly belonging to ankylosaurs and non-avian theropods are also present.

But far more controversial are the numerous short papers that have reported various small archosaurian bones, identified as those of pterosaurs and early birds (e.g., Jurcsák & Popa 1984, Kessler 1984, Kessler & Jurcsák 1984). If you’re interested in the evolution of pterosaurs and Mesozoic birds – or Mesozoic faunas in general – the Cornet deposit is pretty interesting given that it’s Berriasian: that is, from the very start of the Cretaceous, a stage of time about which comparatively little is known.

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Obviously this is close to the Jurassic, so maybe it’s reasonable to think that Jurassic taxa – like archaeopterygid birds – might be present at Cornet, as has been claimed (read on). Of special interest is the suggestion that neornithine birds (‘modern’ birds, if you like) of various kinds are also present at Cornet. The alleged presence of both archaeopterygids and neornithines at the site would show that both archaic and ‘modern’ birds lived alongside one another for a while, and would also show that bird evolution had been pretty explosive around the Jurassic-Cretaceous boundary [the adjacent composite image - which shows an archaeopterygid, Yanornis-like bird and crown-palaeognath alongside one another - alludes to the idea that all these 'grades' of birds might have been contemporaneous]. While the suggested identifications of the Cornet fossils have been doubted, a reanalysis of the fossils has been absent until now. The article here (and the next one) summarises some of the main conclusions of the paper.

* Some of these (originally suggested to belong to valdosaurids or camptosaurids) cannot be identified beyond Iguanodontia, but others have been suggested to belong to Owenodon, a recently named taxon (Galton 2009) named for O. hoggii from the Berriasian Durlston Formation of Dorset, England. Like most other Lower Cretaceous iguanodontians from around the world, O. hoggii was long included in Iguanodon (yet another taxon that has traditionally served as one of those taxonomic wastebaskets: see Naish & Martill (2008) and comments here).

Archaeopterygids at Cornet? No

One of the most bizarre claims made about the Cornet fossils is that Archaeopteryx – otherwise restricted to the Upper Jurassic of Germany (there are some Portugese teeth alleged to belong to this taxon, but their identification is doubtful) – is present in the assemblage (Kessler 1984). This has been widely doubted: to be honest, no-one has taken it that seriously, given the quality of the material.

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And indeed, our reanalysis shows that this suggestion was desperately over-optimistic: it was based on two scrappy bones [shown here, from Dyke et al. (2010)]. One is a long-shafted element, shaped something like a humerus, and the other one is supposed to be the broken end of an ulna (Dyke et al. 2010). The identification of these bones as a humerus and ulna is obviously doubtful. Furthermore, they don’t possess any features that allow them to be recognised as dinosaur bones, let alone those of a theropod, let alone those of a coelurosaur, let alone those of a maniraptoran, let along those of a bird, let alone those of an Archaeopteryx! So, no evidence whatsoever for Archaeopteryx at Cornet: it’s based on some scraps that we identify as Archosauria indet.

‘Modern birds’ at Cornet? Err, no also

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Kessler and colleagues made another remarkable proposal concerning birds at Cornet. They also suggested that members of Neornithes were present in the assemblage. Neornithes is the avian ‘crown group': the clade that includes all living birds and the descendants of their most recent common ancestor. The palaeognaths (ratites, tinamous and extinct relatives) and neognaths (all other ‘modern’ birds).

The nomenclature of the Cornet ‘neornithines’ is fabulously convoluted (hmm. I seem to find myself saying this sort of thing an awful lot these days). A fragmentary femur that ended up with the name Palaeocursornis biharicus was identified as a Cretaceous palaeognath while a partial humerus dubbed Eurolimnornis corneti was supposed to be an ancient, grebe-like neognath. Both of these names were originally attached to a set of remains thought to belong to a bird known as Palaeolimnornis, and this name was itself a replacement for the earlier-used Limnornis. It’s all very confusing and whole papers have been written on sorting out the mess… I’m not going to elaborate; that’s what the paper’s for (Dyke et al. 2010) [the remains in question, with others, are shown in the adjacent illustration, from Dyke et al. (2010)].

Anyway, while this is the kind of extreme miniscule trivia regarded (rightly) by many as being of no real consequence or interest to anyone other than those obsessed with taxonomic stamp collecting, the identification of these fossils is a big deal in terms of what it means for hypotheses of avian evolution. If neornithines really were present as early as the Berriasian, then either bird evolution happened really quickly – explosively, in fact – or, alternatively, most of the major divergences within the bird tree happened earlier in the Mesozoic than generally thought.

Our reanalysis removes evidence claiming to show that neornithines were present as early as the Berriasian: both the alleged palaeognath remains, and the remains of the alleged ‘grebe-like’ neognath, can be identified as bird bones, but that’s about it. In fact, some of them can’t even be identified that far. So, no evidence for neornithines at Cornet. Indeed, other fossils show that neornithines were a Late Cretaceous phenomenon, though they may first have appeared in the Turonian or thereabouts (You et al. 2006) [simplified phylogeny of Avialae and related maniraptorans shown below, from here (compiled by T. R. Holtz, University of Maryland). The crown-group - termed Aves here (used in this sense, synonymous with Neornithes) - seems to have originated late in the Cretaceous].

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Among the various Cornet bones we do identify as those of birds is one specimen (the incomplete distal end of a femur) that looks very much like the corresponding element of Enaliornis from the (substantially younger) Cambridge Greensand of England. Enaliornis is an early member of the mostly marine Mesozoic bird group that includes toothed, flightless, foot-propelled Hesperornis and its relatives (there’s a minor dispute as to whether these birds should be called hesperornithines or hesperornithiforms). The Cornet specimen might, therefore, extend the record of hesperornithines* back to the Berriasian (the previous oldest record is from the Barremian), but the material is so incomplete that it would be unwise to make any strong claims about the significance of the specimen [image below, by John Conway, shows the Late Cretaceous hesperornithid hesperornithine Hesperornis. Early members of the group, like Enaliornis, were not as specialised for foot-propelled diving and may still have had large wings and an ability to fly].

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* And hence the whole of Ornithuromorpha – yikes! (Ornithuromorpha = the clade that includes hesperornithines, Ichthyornis, living birds and several lineages closer to these groups than to enantiornithines).

So, while there are birds at Cornet, there’s no evidence for archaeopterygids, nor for neornithines. Next: the pterosaurs!

For previous Tet Zoo articles on Mesozoic birds and their evolution, see…

Refs – –

Benton, M. J., Cook, E., Grigorescu, D., Popa, E. & Tallodi, E. 1997. Dinosaurs and other tetrapods in an Early Cretaceous bauxite-filled fissure, northwestern Romania. Palaeogeography, Palaeoclimatology, Palaeoecology 130, 275-292.

DYKE, G., BENTON, M., POSMOSANU, E., & NAISH, D. (2010). Early Cretaceous (Berriasian) birds and pterosaurs from the Cornet bauxite mine, Romania Palaeontology DOI: 10.1111/j.1475-4983.2010.00997.x

Galton, P. M. 2009. Notes on Neocomian (Lower Cretaceous) ornithopod dinosaurs from England – Hypsilophodon, Valdosaurus, ‘Camptosaurus‘, ‘Iguanodon‘ – and referred specimens from Romania and elsewhere. Révue de Paléobiologie 28, 211-273.

Jurcsák, T. & Popa, E. 1984. Pterosaurians from the Cretaceous of Cornet, Roumania. In Reif, W.-E. & Westphal, F. (eds) Third Symposium on Mesozoic Terrestrial Ecosystems, Short Papers. Attempto Verlag (Tübingen), pp. 117-118.

Kessler, E. 1984. Lower Cretaceous birds from Cornet (Roumania). In Reif, W.-E. & Westphal, F. (eds) Third Symposium on Mesozoic Terrestrial Ecosystems, Short Papers. Attempto Verlag (Tübingen), pp. 119-121.

– . & Jurcsák, T. 1984. Fossil bird remains in the bauxite from Cornet (Romania, Bihor County). Travaux du Muse´um d’Histoire naturelle Grigore Antipa 25, 393-401.

Naish, D. & Martill, D. M. 2008. Dinosaurs of Great Britain and the role of the Geological Society of London in their discovery: Ornithischia. Journal of the Geological Society, London 165, 613-623.

Posmosanu, E. & Cook, E. 2000. Vertebrate taphonomy and dinosaur palaeopathology from a lower Cretaceous bauxite lens, north west Romania. Oryctos 3, 39-51.

You, H.-l., Lamanna, M. C., Harris, J. D., Chiappe, L. M., O’Connor, J., Ji, S.-a., Lü, J.-c., Yuan, C.-x., Zhang, X., Lacovara, K. J., Dodson, P. & Ji, Q. 2006. A nearly modern amphibious bird from the Early Cretaceous of northwestern China. Science 312, 1640-1643.

Comments

  1. #1 David Marjanović
    September 27, 2010

    Neornithes is the avian ‘crown group': the clade that includes all living birds and the descendants of their most recent common ancestor. Basically, it’s palaeognaths (ratites, tinamous and extinct relatives) and neognaths (all other ‘modern’ birds).

    Not just “basically”. Palaeo- and Neognathae have branch-based definition, so every neornithean is a palaeognath, a neognath, or their last common ancestor.

    The crown-group – termed Aves here (used in this sense, essentially synonymous with Neornithes)

    Not just “essentially” — precisely.

    image below, by John Conway, shows the Late Cretaceous hesperornithid hesperornithine Hesperornis.

    Great drawing (as is yours and Tim’s colouring of it), but… what is the point of catching an Enchodus that is way too big to swallow? It wouldn’t even fit into the ribcage as far as I can tell.

    (Ornithuromorpha = the branch-based clade that includes hesperornithines, Ichthyornis, living birds and several lineages closer to these groups than to enantiornithines).

    Has Ornithuromorpha got such a definition meanwhile? The only two (!) I can remember are node-based. The branch-based one is Euornithes Sereno 1998.

    (Why don’t people use it more often? Because it was published in the N. Jb. Geol. Paläont. Abh.?)

  2. #2 Ryan S.
    September 27, 2010

    I have become a big fan of tet-zoo and it has encouraged me to learn more about the tetrapods around me. The other day, mowing the grass in eastern Missouri, I almost stepped on a Garter snake (in this case I would guess Thamnophis sirtalis pallidulus). It had a bright red tongue with black tip.

    I haven’t seen a snake in my yard since a Common Black snake (Elaphe obsoleta) sunned itself on my driveway, almost totally flattened, eight years ago.

    I had been watching a family of Northern Cardinals (Cardinalis cardinalis) use my birdfeeder and feed their two juveniles. I found a skull of what I believe to be one of the juveniles and wondered if that was the reason for finding the garter snake…preparing for hibernation?

    Later, I mowed over some furrows caused by an Eastern Mole (Scalopus Aquaticus). He’s digging his deep-producer holes, getting ready for the winter and creating mounds of dirt above them.

    My greatest tetrapod story is using a net to catch an Alligator Snapping Turtle (Macrochelys temminckii) when I was 14 in a pond near my house. He didn’t eat anything while living in my small plastic pool so I returned him to the pond.

    I also once caught an American Bullfrog (Rana catesbeiana) who devoured a large toad (probably Bufo americanus) and had a powerful enough jump to escape from a metal trash can covered with a net in the middle of the night.

    They’re draining all the ponds around here and I feel sorry for the kids who can’t poke around them like I used to.

  3. #3 Darren Naish
    September 27, 2010

    David: thanks for corrections, I’ve made a few edits to account for them. As for the question of why the Hesperornis is catching a fish that looks too big, I’m gonna point you here and here.

    Ryan: I’m pleased to be an inspiration. Remarkable creatures are all around us, consider yourself among the enlightened if you take time to observe (and learn about) them. Did you keep (and/or photograph) the cardinal skull? I hope so!

  4. #4 Stu of the Peak
    September 27, 2010

    Is that a booby in the foreground?

  5. #5 Rob Jase
    September 27, 2010

    You & David Martill have to find a reason to get together for a podcast about these somewhere.

  6. #6 Mickey Mortimer
    September 27, 2010

    So Palaeocursornis and Eurolimnornis “can be identified as bird bones, but that’s about it”? How does the new paper account for the features Hope (2002) noted, like the patellar sulcus and large tibiofibular crest in Palaeocursornis, and rounded distal condyles and well developed brachial fossa in Eurolimnornis? These would seem to place the taxa well within Ornithuromorpha.

  7. #7 Gareth Dyke
    September 28, 2010

    Mickey: thanks – good morning!
    I know that Sylvia Hope (2002) placed some of Kessler’s bird taxa higher up the tree than we did, but when I examined these specimens I could not determine the characters she pointed to. So, went for a more ‘conservative’ determination. I think that with a ‘these are birds’ id for the specimens, the door is open for others to check out the material and come up with more precise assignments. I’d totally recommend anyone to make a trip to Oradea: fun town!.
    At the moment, the Museum collection is housed in an old Bishop’s Palace (soon due to move, I understand).
    Rob: David Martill? I didn’t see anyone in short shorts and a bum bag in Oradea when I was working on these fossils.

  8. #8 Don Cox
    September 28, 2010

    Please could you post diagrams like that family tree as GIFs, not as JPGs. They don’t need millions of colours, and JPGs make the text blurry.

    Bigger would be good, too.

  9. #9 David Marjanović
    September 28, 2010

    As for the question of why the Hesperornis is catching a fish that looks too big, I’m gonna point you here and here.

    Heh. Good point!

    When the eyes are bigger than the distance between the jaw joints… :-)

  10. #10 Mickey Mortimer
    September 28, 2010

    Thanks for the quick reply, Gareth. I suppose if you couldn’t see the features in the material itself, I’d have to say it’s quite frustrating when illustrations (such as the one reproduced above of Palaeocursornis and Eurolimnornis) don’t accurately represent the fossils. Because features such as the prominent, posteriorly extensive tibiofibular crest seem obvious in the figure. Of course I haven’t read your paper yet, so maybe it’s explained by breakage of the medial condyle or something.

  11. #11 Ryan S.
    September 28, 2010

    Didn’t photograph the skull. Tried to photograph the snake but he was gone by the time I grabbed the camera. I did get a nice shot of a mole postmortem…no comment on cause of death.

  12. #12 Willem van der Merwe
    September 29, 2010

    Re the Hesperornis and the fish: I’ve seen a Saddlebilled Stork swallow a turtle that was about as wide as its entire torso. And the stork swallowed it *successfully* – we saw it go down – slowly – all the way. And it (the stork, not the turtle) didn’t even look particularly discomfited.

  13. #13 Katharine
    September 29, 2010

    What the crap is the deal with Romania and extinct flying reptiles?

  14. #14 Tim Morris
    September 30, 2010

    @ Katherine – Because ve sink zey’re vonderful, a ha ha!

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