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In pursuit of Early Cretaceous crocodyliforms in southern England (part II): of Vectisuchus and Leiokarinosuchus, Bernissartia and the hylaeochampsids

The views expressed are those of the author and are not necessarily those of Scientific American.


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In the previous article we looked at Wealden goniopholidids, focusing in particular on the new taxa named by Steve Salisbury and myself in the review of Wealden crocodyliforms we published last year (Salisbury & Naish 2011). Having gotten some of the relevant taxa out of the way, we now need to crack on and get through the remainder.

We begin with Vectisuchus leptognathus, a relatively long-snouted goniopholidid (though read on) from the Vectis Formation collected by Steve Hutt in 1977 and described by Buffetaut & Hutt (1980). The type (and only) specimen is, unfortunately, not readable available if you’re based in the UK since it was sold to the Staatliches Museum für Naturkunde (SMNS) in Stuttgart (Germany) in 1979. The original description states that some of the material discovered in the field couldn’t be collected due to cliff collapse caused by inclement weather, but material present at the SMNS shows that some of this was collected, and hence obtained by the SMNS, at some stage afterwards (Salisbury & Naish 2011).

Holotype skull of Vectisuchus leptognathus in (A) dorsal and (B) ventral views. From Buffetaut & Hutt (1980).

Anyway, Vectisuchus is a slender-snouted animal where the rostrum is well demarcated from the rest of the skull. The snout and lower jaw tip are expanded, and the large, rounded eye sockets are directed rostrolaterally (meaning that they point both forwards and sideways at the same time). It wasn’t an especially large animal, with a skull just 18 cm long and a total length estimated at 1.2 m.

An especially interesting feature of the specimen (though it isn’t unique to this taxon within Goniopholididae) is that its forelimbs are more elongate than is usual for mesoeucrocodylians*: they’re actually 10-20% longer than the hindlimbs, whereas the reverse is true in eusuchians. So far as I know, nobody has suggested a specific ‘function’ for these elongate forelimbs. I don’t think goniopholidids were reaching up into vegetation, or using their elevated forequarters to keep heavy objects carried in the jaws off the ground (two behaviours that have been linked with elongate forelimbs in other tetrapods). Other possibilities are that they were especially good at ‘poling’ along with the forelimbs while moving on submerged substrates, that they needed to stand up tall, or raise the snout especially high, while feeding or displaying.

* Mesoeucrocodylia = the crocodyliform clade that includes all taxa closer to Crocodylus niloticus than to Protosuchus richardsoni.

This never happened. The gigantic pholidosaurid (or pholidosaurid relative) Sarcosuchus roughly to scale with some Wealden crocodyliforms. Hey, it's just for fun.

Incidentally, while we include Vectisuchus within Goniopholididae, there are indications that this may not be correct, since Jouve et al. (2006), Jouve (2009) and De Andrande et al. (2012) find this animal to be closer to Pholidosauridae (and their kin). Pholidosaurids are long-snouted crocodyliforms often found in phylogenies to be close to the also (typically) long-snouted dyrosaurids and thalattosuchians: the gigantic Sarcosuchus is probably the most famous member of the group. However, anyone deeply immersed in crocodyliform phylogeny and systematics will know that the term Pholidosauridae is currently somewhat problematic. I have to gloss over that issue for now and promise to come back to it later.

Weird little Leiokarinosuchus

Holotype skull (NHMUK 28966) of Leiokarinosuchus brookensis Salisbury & Naish, 2011, in (A-B) dorsal and (C-D) ventral views.

Of the three new taxa named in our review, the most poorly known is Leiokarinosuchus brookensis Salisbury & Naish, 2011. It’s based on a partial skull (lacking essentially the whole of the rostrum) and its associated cervical vertebrae and osteoderms. This specimen was found in the Brook Bay region of the Isle of Wight (and hence is presumably from the Wessex Formation), was purchased in 1855 and has been little discussed ever since.

Lydekker (1887) referred it to the German Obernkirchen Sandstone species Pholidosaurus meyeri, one of the pholidosaurids. So, thanks to this skull, Wealden workers have often listed pholidosaurids as components of Wealden faunas. Our examination showed, however, that the Brook Bay skull is no pholidosaurid – it lacks the characteristic features of this group and is, in fact, far more likely to be a long-snouted goniopholidid (Salisbury & Naish 2011).

Several features make the skull rather different from the skulls of pholidosaurids, and they also make it weird and worthy of recognition as a new taxon. While some of the preserved skull bones are covered with the bone pitting that’s fairly normal for crocodyliforms, the preserved, posterior part of the dentary is smooth (as they are in Anteophthalmosuchus), and so are the bones on the roof of the skull. What’s more, the bones around the supratemporal fenestrae smoothly slope ‘into’ the edges of these openings. The occipital condyle is proportionally small, a feature also seen in Anteophthalmosuchus (Salisbury & Naish 2011). Unusual features are also seen in the dorsal osteoderms: they lack the articular processes seen in goniopholidids, and their lateral sections are inclined relative to the medial part – a feature seen elsewhere in Bernissartia and some eusuchians, but not in goniopholidids.

Leiokarinosuchus is thus a rather odd little animal. It preserves a combination of unusual characters and can’t be convincingly slotted into any particular crocodyliform clade, though does seem goniopholidid-like in several details and might be a member of this group. The smooth roof of the skull and the weird form of the bones around the supratemporal fenestrae certainly suggest that it warrants distinct taxonomic status, and the generic name we went for means ‘smooth-headed crocodile’ (or ‘bald-headed crocodile’).

Atoposaurids in the Wealden?

Several specimens demonstrate that members of another crocodyliform clade, Atoposauridae, were also present in Wealden assemblages. Atoposaurids are all small (something like 50-100 cm long), short-snouted crocodyliforms: like goniopholidids and Bernissartia (read on), they’re stem-neosuchians – early members of the clade that also includes the living crocodyliform lineages.

Theriosuchus braincase from the Wealden, from Buffetaut (1983), in (A) dorsal and (B) posterior views.

The Wealden atoposaurid remains – they include teeth from the Ashdown and Wadhurst Clay formations (both part of the Hastings Group) as well as a partial braincase from the Wessex Formation – all seem referable to Theriosuchus, a geologically long-lived and apparently widespread atoposaurid that’s currently thought to have been around from the Late Jurassic to the latest Late Cretaceous (Brinkmann 1992, Schwarz & Salisbury 2005, Martin et al. 2010). These belong to at least five species (T. pusillus Owen, 1879, T. ibericus Brinkmann, 1992, T. guimarotae Schwarz & Salisbury 2005, T. sympiestodon Martin et al., 2010 and T. grandinaris Lauprasert et al., 2011). The Wealden Theriosuchus material was first identified as such by Peter Wellnhofer in 1980 and was later described by Buffetaut (1983); we agreed with Buffetaut that, while the Wessex Formation specimen looks most like T. pusillus from the Purbeck Limestone Group, it can’t be identified precisely in the absence of better material (Salisbury & Naish 2011).

Atoposaurids, goniopholidids, Bernissartia and hylaeochampsids are all close relatives of Crocodylia, the crocodyliform crown-group. The possible branching order of these lineages is shown here in this highly simplified cladogram. An interesting thing here is that many of the lineages concerned consist of small-bodied taxa. Based on Salisbury et al. (2006) and other sources.

Bernissartia and other ‘bernissartids’

One of the best known Lower Cretaceous European crocodyliforms has to be little Bernissartia, and I say this because most sources on these animals mention, discuss or illustrate the near-complete skeleton of B. fagesii Dollo, 1883 [shown below]. It was discovered in the same coal mine at Bernissart, Belgium, that also yielded all those Iguanodon skeletons. Thanks to this specimen and one or two others, we know that Bernissartia was small (c. 60 cm total length), with vertebral, osteoderm and palatal characters that put it close to the origin of Eusuchia (e.g., Buffetaut 1975, Norell & Clark 1990, Salisbury et al. 2006). Its posterior, so-called tribodont teeth (these have rounded cusps where the enamel on the apical half is ornamented with vertical striations) are unlike those of any contemporary crocodyliform and can be readily identified when found in isolation.

The holotype specimen of Bernissartia fagesii, as photographed at the IRSNB, Brussels.

Indeed, a large number of fragmentary remains from Upper Jurassic and Lower Cretaceous localities across western Europe have been identified as those of Bernissartia or Bernissartia-like ‘bernissartids’ (see Salisbury & Naish 2011). In the Wealden, isolated teeth and a partial skeleton show that Bernissartia is present in the Hastings Group (most likely in the Ashdown Formation), the Lower Weald Clay Formation, and the Wessex Formation. In other words, ‘bernissartids’ of some sort were present in southern England for virtually the whole time that the Wealden sediments were being deposited. Better remains are needed to identify them to species level. A small, near-complete skull of Bernissartia-like crocodyliform has recently been discovered on the Isle of Wight and is currently under study by Steve Sweetman and colleagues.

Hylaeochampsids and other eusuchians

Finally, we come to the hylaeochampsids, for the Wealden also gives us Hylaeochampsa vectiana, a crocodyliform named by Richard Owen in 1874 for yet another partial skull. Hylaeochampsa is from the Wessex Formation (not the Vectis Formation, as stated by Clark & Norell (1992)) and could potentially have lived alongside Anteophthalmosuchus and Leiokarinosuchus.

Skulls of the hylaeochampsid Iharkutosuchus makadii, photographed at the Hungarian Natural History Museum, Budapest. In total length, each skull is about 10 cm long. Lots of weirdness here.

The only known specimen of Hylaeochampsa is missing its rostrum as well as its teeth; furthermore, there has been a reasonable amount of disagreement about the homology of the large openings on the posterior part of its palate. A few recently discovered crocodyliforms seem to be close relatives of Hylaeochampsa, necessitating the recognition of a Hylaeochampsidae. Both Iharkutosuchus makadii, a hylaeochampsid named from the Upper Cretaceous of Hungary in 2007 (Ősi et al. 2007, Ősi 2008), and the several species of Acynodon (suggested to be part of Hylaeochampsidae by Turner & Brochu (2010)), are smallish, short-snouted forms with enlarged, multi-cusped posterior teeth, so it looks very likely that Hylaeochampsa was like this as well. Buscalioni et al. (2011) have recently regarded Pietraroiasuchus and Pachycheilosuchus as hylaeochampsids as well.

Incomplete holotype skull (NHMUK R177) of Hylaeochampsa vectiana Owen, 1874, in (A) dorsal, (B) ventral, (C) posterior, and (D) left lateral views. From Salisbury & Naish (2011).

A number of skull features – most importantly the enclosure of the choana within the pterygoid bones – show that Hylaeochampsa (and its relatives) is part of Eusuchia, the clade that includes Crocodylia and several closely related lineages. This is important, since it shows that eusuchians had appeared by the Barremian at least, and that they were present in the Northern Hemisphere at this time (some other Early Cretaceous eusuchians are Gondwanan).

Several eusuchian odds and ends – mostly procoelous vertebrae – are known from various Wealden Supergroup units, including the Hastings Group. One such specimen (a string of 12 articulated vertebrae) was named Heterosuchus valdensis by Seeley (1887) and has sometimes been regarded as synonymous with Hylaeochampsa. While this isn’t impossible, the two are very different in age, there’s no overlapping evidence that might support it, and a lack of unique features means that Heterosuchus has to be regarded as a nomen dubium (Salisbury & Naish 2011).

While there’s even more that could be said about Wealden crocodyliforms – our chapter is a not-insubstantial 64 pages long – I think this article and the previous one do a reasonable job of summarising the contents of Salisbury & Naish (2011). Our review is certainly not the last word on Wealden crocodyliforms; as a review of where we’re at right now, it’s hopefully the start of a new phase in our work on the phylogeny, systematics and ecology of these animals.

For some previous Tet Zoo coverage of crocodylomorphs (wholly crocodyliforms, and mostly crocodylians), see…

Massive thanks to my co-author, Steve Salisbury, for his work in generating, and help in providing, the images used here.

Refs – -

Andrade, M. B., Edmonds, R., Benton, M. J. & Schouten, R. 2012. A new Berriasian species of Goniopholis (Mesoeucrocodylia, Neosuchia) from England, and a review of the genus. Zoological Journal of the Linnean Society 163, S66–S108.

Brinkmann, W. 1992. Die Krokodilier-Fauna aus der Unter-Kreide (Ober-Barremium) von Uña (Provinz Cuenca, Spanien). Berliner Geowissenschaftliche Abhandlungen, Reihe E 5, 1-123.

Buffetaut, E. 1975. Sur l’anatomie et la position systematique de Bernissartia fagesii Dollo, L., 1883, crocodilien Wealdien de Bernissart, Belque. Bulletin de l’Institute Royal des Sciences Naturelles de Belgique, Sciences de la Terre 51, 1-20.

- . 1983. The crocodilian Theriosuchus Owen, 1879 in the Wealden of England. Bulletin of the British Museum (Natural History) Geology 37, 93-97.

- . & Hutt, S. 1980. Vectisuchus leptognathus, n. g. n. sp., a slender-snouted goniopholid crocodilian from the Wealden of the Isle of Wight. Neues Jahrbuch für Geologie und Paläeontologie Monatshefte 7, 385-390.

Buscalioni, A. D., Piras, P., Vullo, R., Signore, M. & Barbera, C. 2011. Early eusuchia crocodylomorpha from the vertebrate-rich Plattenkalk of Pietraroia (Lower Albian, southern Apennines, Italy). Zoological Journal of the Linnean Society 163, S199–S227.

Clark, J. M. & Norell, M. A. 1992. The Early Cretaceous crocodylomorph Hylaeochampsa vectiana from the Wealden of the Isle of Wight. American Museum Novitates 3032, 1-19.

Jouve S. 2009. The skull of Teleosaurus cadomensis (Crocodylomorpha; Thalattosuchia), and phylogenetic analysis of Thalattosuchia. Journal of Vertebrate Paleontology 29, 88-102.

Jouve, S., Iarochene, M., Bouya, B. & Amaghzaz, M. 2006. A new species of Dyrosaurus (Crocodylomorpha, Dyrosauridae) from the early Eocene of Morocco: phylogenetic implications. Zoological Journal of the Linnean Society 148, 603-656.

Lydekker, R. 1887. Note on the Hordwell and other crocodilians. Geological Magazine 3, 307-312.

Martin, J. E, Rabi, M. & Csiki, Z. 2010. Survival of Theriosuchus (Mesoeucrocodylia: Atoposauridae) in a Late Cretaceous archipelago: a new species from the Maastrichtian of Romania. Naturwissenschaften 97, 845-854.

Norell, M. A. & Clark, J. M. 1990. A reanalysis of Bernissartia fagesii, with comments on its phylogenetic position and its bearing on the origin and diagnosis of the Eusuchia. Bulletin de L’Institut Royal des Sciences Naturelles de Belgique, Sciences de la Terre 60, 115-128.

Ősi, A. 2008. Cranial osteology of Iharkutosuchus makadii, a Late Cretaceous basal eusuchian crocodyliform from Hungary. Neues Jahrbuch für Geologie und Paläontologie, Abhandlungen 248, 279-299.

- ., Clark, J. M. and Weishampel, D. B. 2007. First report on a new basal eusuchian crocodyliform with multicusped teeth from the Upper Cretaceous (Santonian) of Hungary. Neues Jahrbuch fur Geologie und Palaontologie, Abhandlungen 243, 169–177.

Salisbury, S. W., Molnar, R. E., Frey, E. & Willis, P. M. A. 2006. The origin of modern crocodyliforms: new evidence from the Cretaceous of Australia. Proceedings of the Royal Society of London, Series B 273, 2439-2448.

- . & Naish, D. 2011. Crocodilians. In Batten, D. J. (eds). English Wealden Fossils. The Palaeontological Association (London). pp. 305-369.

Schwarz, D. & Salisbury, S. W. 2005. A new species of Theriosuchus (Atoposauridae, Crocodylomorpha) from the Late Jurassic (Kimmeridgian) of Guimarota, Portugal. Gebios 38, 779-802.

Seeley, H. G. 1887. On Heterosuchus valdensis, Seeley, a procoelian crocodile from the Hastings Sand of Hastings. Quarterly Journal of the Geological Society of London 43, 212-215.

Turner, A. H. & Brochu, C. 2010. A reevaluation of the crocodyliform Acynodon from the Late Cretaceous of Europe. Journal of Vertebrate Paleontology 28 (Supplement to No. 3), 178A.

Darren Naish About the Author: Darren Naish is a science writer, technical editor and palaeozoologist (affiliated with the University of Southampton, UK). He mostly works on Cretaceous dinosaurs and pterosaurs but has an avid interest in all things tetrapod. His publications can be downloaded at darrennaish.wordpress.com. He has been blogging at Tetrapod Zoology since 2006. Check out the Tet Zoo podcast at tetzoo.com!

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The views expressed are those of the author and are not necessarily those of Scientific American.





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  1. 1. David Marjanović 9:01 am 10/1/2012

    anyone deeply immersed in crocodyliform phylogeny and systematics will know

    I just love that. :-)

    Link to this
  2. 2. BrianL 4:11 pm 10/1/2012

    I suspect you may finally have reached a subject so specialized that none of your commenters really have anything to add, ask or correct. It’s quite a feat, but seems to result in very few comments indeed.

    I might just be speaking for myself here, though.

    Link to this
  3. 3. Dartian 3:13 am 10/2/2012

    Darren:
    One of the best known Lower Cretaceous European crocodyliforms has to be little Bernissartia”

    What do we know about its palaeoecology? Is there reason to believe, for example, that Bernissartia was significantly more terrestrial than extant crocodyliforms?

    Link to this
  4. 4. naishd 4:07 am 10/2/2012

    BrianL: ha ha, you may be right. Or are you (since, here we are, on comment # 4 already! That’s more that some other SciAm blogs get).

    Palaeoecology of Bernissartia: good question. So far as I know, we ‘know’ nothing more than inference. Those tribodont teeth have often been said to be indicative of a diet that involves the eating of shelled things, like bivalves, crustaceans and/or gastropods. Extant crocs and lizards with roundish teeth suited for crushing things are ecological generalists, eating most things within a suitable size range, so I would guess that Bernissartia did this as well. It’s always been assumed to be amphibious (based on a general similarity in proportions to extant crocodylians) – I don’t think there’s any reason to think that it was especially terrestrial. If you’re thinking this because of a possible similarity with small, semi-terrestrial modern crocs like Osteolaemus, note that Bernissartia lacks the relatively deep skull and heavily ossified palpebrals of such forms.

    All in all, more study is needed, though.

    Darren

    Link to this
  5. 5. Dartian 5:09 am 10/2/2012

    Darren:
    If you’re thinking this because of a possible similarity with small, semi-terrestrial modern crocs like Osteolaemus”

    Actually, what I rather had in mind (in terms of possible extant ecological analogues) were certain lizards such as semi-aquatic monitors and the caiman lizards Dracaena. I’m admittedly well out of my area of expertise here, but my impression is that squamate/lizard diversity in the Mesozoic – at least in non-marine settings – was not as high as in the Cenozoic (if that’s not the case, feel free to correct me). I’d thus not be surprised to learn that Mesozoic crocodyliforms occupied econiches that today are mainly filled by large lizards.

    Link to this
  6. 6. David Marjanović 7:46 am 10/2/2012

    Dracaena reminds me of the less extreme ones among the champsosaurs.

    Link to this
  7. 7. naishd 9:26 am 10/2/2012

    Was Bernissartia (and similar crocs) similar to Dracaena in lifestyle/ecology? Hey, that’s an interesting idea. My gut feeling, however, is that the similarities weren’t tremendously strong, since Bernissartia and such look far more ‘croc-like’ in skull form (even the more three-dimensional of the ‘bernissartid’ skulls are flatter-snouted that those of Dracaena). I mean, I imagine them hiding in pools and hunting aquatic prey more than Dracaena does. More importantly, Dracaena forages in trees for a large part of the year; I don’t think ‘bernissartids’ were doing this.

    By the way, anyone have an opinion on whether it should it be ‘bernissartids’ or ‘bernissartiids’?

    Darren

    Link to this
  8. 8. Andreas Johansson 11:01 am 10/3/2012

    A family based on Bernissartia ought be named Bernissartiidae, and its members accordingly “bernissartiids”.

    Short version as to why: Bernissartia looks like one of the innumerable Latin 1st decl feminines in -a, so ought have a genitive “Bernissartiae”, and the ICZN then tells us to replace the genitival ending (here -ae) with the suffix -idae to make a family name.

    Link to this
  9. 9. David Marjanović 5:09 am 10/4/2012

    Bernissartiidae

    Yes. Short version: It’s Bernissartia, not Bernissarta.

    Link to this
  10. 10. kuartus 11:31 pm 10/4/2012

    Question. How many crocodylomorph genera are known from the fossil record, total?

    Link to this
  11. 11. David Marjanović 11:38 am 10/5/2012

    A shitload?

    Perhaps 50? But genera are a very subjective “unit”.

    Link to this

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