Same old story: Naish plans to blog on long-promised subjects, Naish gets distracted by cool new stuff, Naish ends up writing about cool new stuff and delaying long-promised subjects for even longer. Here, inspired by a paper I recently published with University of Bristol’s Barbara Sánchez-Hernández and Mike Benton (Sánchez-Hernández et al. 2007), I’ve made a concerted effort to finish writing about the Mesozoic tetrapods of the Galve region of Teruel Province, NE Spain. In the previous post I covered crocodyliforms and pterosaurs. This time we get to the dinosaurs [adjacent image shows some heterodontosaurids: painting by Greg Paul]. As nice as dinosaurs are, I have to say that something far bigger and more newsworthy is on the horizon – it’s coming soon here on the blog, and I hope that it will generate a lot of interest. Stay tuned.
By the way, today I saw two Roe deer Capreolus capreolus. Both were feeding in the middle of a field: apparently a ‘new’ behaviour that they indulge in regularly now. And in a shallow pool adjacent to the M27 near Portsmouth, I counted eight Little egrets Egretta garzetta: this bird was nationally very rare prior to the 1980s but now occurs everywhere in Britain; it’s been breeding here since the late 1990s. Anyway…
Among the dinosaurs of Galve, we report new material of theropods, sauropods and ornithischians (Sánchez-Hernández et al. 2007). I’ll keep it brief – as who wants to hear more about theropods and sauropods – but one particularly interesting new discovery we report is the presence of (drumroll)… spinosaurines. That’s right, not just spinosaurids (the group that includes both baryonychines and spinosaurines), but spinosaurines. The only well known spinosaurines are Spinosaurus from northern Africa and Irritator from Brazil, and this is the first record of the group from Europe (to my knowledge, and disregarding old, incorrect suggestions that Becklespinax and other such taxa might be close kin of Spinosaurus). This is significant, as – assuming that we are correct in our identification – it now means that spinosaurines have a fossil record that extends as far back as that of their sister-taxon, Baryonychinae. It also means that the oldest spinosaurines are European. Furthermore, the teeth aren’t particularly big, with crown heights that are mostly less than 20 mm. Are the teeth from juveniles, or do they represent a small-bodied taxon? This is an awful lot to stack up on a bunch of isolated teeth, sure, but I strongly disagree with the idea that we should just sweep this sort of evidence under the carpet and pretend it doesn’t exist [adjacent image shows the mounted Spinosaurus holotype, photographed in Munich prior to 1944].
Teeth belonging to baryonychines, allosauroids, dromaeosaurids and indetermine coelurosaurs have also been recovered at some of the Galve sites. As is the case with several other Spanish baryonychine teeth, the Galve specimens differ in detail from those of Baryonyx walkeri, and might belong to another species (for more on this idea seen Ruiz-Omeñaca et al. 1997, Naish 2002 and Naish & Martill 2007) [adjacent image shows multiple hypothetical Baryonyx species]. Some weird coelurosaur teeth from the Galve outcrops of the El Castellar Formation look a bit like Upper Cretaceous teeth that Sankey et al. (2002) identified as avian, but that’s as far as we could go.
Sauropods at Galve are represented by Aragosaurus ischiaticus, Galveosaurus herreroi and the immense Turiasaurus riodevensis [I blogged on Turiasaurus at ver 1 here. Though well behind the behemoth that is Amphicoelias fragillimus (go here for more on that taxon), it is one of the biggest known sauropods]. Aragosaurus has been identified as a camarasaurid, a titanosaur and (most recently) as a eusauropod of uncertain affinities, Galveosaurus was described as a cetiosaurid but later argued to be a basal macronarian (Barco et al. 2006), and Turiasaurus was argued by its describers to represent a new clade close to neosauropod ancestry, Turiasauria (Royo-Torres et al. 2006). The last study also concluded that Galveosaurus was a turiasaur, and not a cetiosaurid or macronarian.
Galveosaurus has taken centre stage in a debate on ethics and publishing rights. Barbara published a 2005 paper on this taxon, naming it Galveosaurus herreroi, in the journal Zootaxa (Sánchez-Hernández 2005). In the same year, a team led by José Luis Barco published a less formal article in the magazine Naturaleza Aragonesa (Barco et al. 2005), and here they named the same taxon Galvesaurus herreroi (viz, with a difference of one letter). There is a lot that could be said about this case and both sides have presented different arguments. I was totally unaware of this situation when I began working with Barbara and am keen to avoid getting involved in what appears to be an internecine debate. Working on dinosaurs is not as fun as it might be: there are apparently not enough specimens to go round [adjacent image shows Barbara's diagrammatic interpretation of the Galveosaurus remains, though I would argue that she shouldn't have used Carol Abraczinskas' silhouette of Shunosaurus as a template].
Anyway, besides these named taxa, isolated remains referred to camarasaurids, brachiosaurids and diplodocids have also been reported from the Galve area. We re-evaluated this and argued that, while some of the isolated sauropod material from Galve can’t definitely be identified beyond Eusauropoda, there is material from the locality that appears to belong to a Camarasaurus-like taxon, and to a titanosaur (Sánchez-Hernández et al. 2007). The Camarasaurus-like taxon is represented only by teeth from the El Castellar Formation: they are more like the teeth of Camarasaurus than the teeth of any other sauropod, but their Hauterivian-Barremian age makes them substantially younger than Camarasaurus, and hence likely to belong to a separate taxon. Here we come again to that ‘cryptic diversity’ theme that I keep coming back to: the idea that the fossil record includes tons of material that surely belongs to new species, but species based on material that is generally too poor for us to name. Finally on sauropods, our article was submitted long before Rafael Royo-Torres and colleagues published Turiasaurus (Royo-Torres et al. 2006). Could it be then that some of our remains belong to turiasaurs? I have to say that it doesn’t look like it.
Finally, we come to ornithischians, a dinosaur group that has pretty much been a no-show on the blog so far, but not because I don’t like them. Come on, how could anyone not be interested in all those elaborately crested hadrosaurs, the stegosaurs, the ceratopsians… it’s just that I’ve obviously been too busy with lizards, mice, passerines and sheep Of the Galve material that we describe, arguably the most interesting is that belonging to heterodontosaurids. These are a mostly Lower Jurassic clade, best known from southern Africa, but with an undoubted presence in the form of little Echinodon becklesii from (probably) the Berriasian Lulworth Formation of Dorset.
Conventionally argued to be basal ornithopods (predominantly because of tradition, and more recently because of two not-particularly-convincing cranial characters), several authors (including Naish & Martill 2001) have interpreted heterodontosaurids as close relatives of marginocephalians, and the recently named Yinlong downsi led Xu et al. (2006) to formally recognise a heterodontosaurid + marginocephalian clade that they named Heterodontosauriformes (skull of Yinlong shown in adjacent photo). A soon-to-be-published analysis (by ornithischian worker Richard Butler) argues instead that heterodontosaurids are right down at the base of Ornithischia, and while we’re here it’s worth noting that several major studies on this fascinating group are due to be published within the next few years.
Again, the Galve material isn’t great: we’re talking about isolated teeth. As Richard reminds me on occasion, saying that isolated ornithischian teeth are of heterodontosaurid identity is dicey given that several ornithischian clades have teeth of this sort. Even so, the Galve teeth look more like those of heterodontosaurids than those of anything else, and they’re also different from the teeth of Echinodon. The Galve taxon must have been tiny, with teeth that are less than 6 mm in crown height. As we discuss in the paper, various other ornithischian teeth from Lower Cretaceous Spain also seem referable to heterodontosaurids.
So there we have it. While the material we describe is certainly not the best in the world, it is potentially significant in suggesting some new range extensions, and in hinting at some previously undocumented taxa. As is so often the case, we wait for better discoveries to confirm our identifications.
Refs – –
Barco, J. L. , Canudo, J. I. & Cuenca-Bescós, G. 2006. Descripción de las vértebras cervicales de Galvesaurus herreroi Barco, Canudo, Cuenca-Bescos & Ruiz-Omeñaca, 2005 (Dinosauria, Sauropoda) del tránsito Jurásico-Cretácico en Galve (Teruel, Aragón, España). Revista Española de Paleontología 21, 189-205.
Naish, D. 2002. Thecocoelurians, calamosaurs and Europe’s largest sauropod: the latest on the Isle of Wight’s dinosaurs. Dino Press 7, 85-95.
– . & Martill, D. M. 2001. Ornithopod dinosaurs. In Martill, D. M. & Naish, D. (eds) Dinosaurs of the Isle of Wight. The Palaeontological Association (London), pp. 60-132.
– . & Martill, D. M. 2007. Dinosaurs of Great Britain and the role of the Geological Society of London in their discovery: basal Dinosauria and Saurischia. Journal of the Geological Society, London 164, 493-510.
Royo-Torres, R., Cobos, A. & Alcalá, L. 2006. A giant European dinosaur and a new sauropod clade. Science 314, 1925-1927.
Ruiz-Omeñaca, J. I., Canudo, J. I. & Cuenca-Bescós, G. 1997. First evidence of baryonychid dinosaurs (Saurischia: Theropoda) in the upper Barremian (Lower Cretaceous) of Vallipon (Castellote, Teruel, Spain). Beca del Museo de Mas de las Matas 17, 201-223.
Sánchez-Hernández, B. 2005. Galveosaurus herreroi, a new sauropod dinosaur from Villar del Arzobispo Formation (Tithonian-Berriasian) of Spain. Zootaxa 1034, 1-20.
– ., Benton, M. J. & Naish, D. 2007. Dinosaurs and other fossil vertebrates from the Late Jurassic and Early Cretaceous of the Galve area, NE Spain. Palaeogeography, Palaeoclimatology, Palaeoecology 249, 180-215.
Xu, X., Forster, C. A., Clark, J. M. & Mo, J. 2006. A basal ceratopsian with transitional features from the Late Jurassic of northwestern China. Proceedings of the Royal Society of London B 273, 2135-2140.