The Cretaceous birds and pterosaurs of Cornet: part I, the birds

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].

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.

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.

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

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].

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].

* 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...

• Tet Zoo picture of the day # 24 [on archaeopterygids]
• The new Crato Formation enantiornithine
• A stunning new Mesozoic bird... well, new-ish
• Epidexipteryx: bizarre little strap-feathered maniraptoran
• Long and Schouten's Feathered Dinosaurs, a review
• Cyril Walker
• The Mesozoic birds with weird, plastic-strip-style tail structures
• Alexornis and other 'alexornithiforms'
• Aberratiodontus: worst paper ever?

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.