Identifying Parapsicephalus purdoni.

So figured it was about time I produced a palaeontological blog post for my blog with palaeo in the title, and what better topic for me to cover/shill than my recent paper into the taxonomy of the British pterosaur Parapsicephalus purdoni (just in case anyone reading this isn’t one of the fraternity, you can pronounce that as either Par-Ap-Si-Kef-Al-Us or Par-Ap-Si-Sef-Al-Us, pick your poison). While I’ve published several papers before, this is the most significant at time of writing. So, let’s lay out what Parapsicephalus is and why I spent several years staring at it.

 

*note. Due to copyright, I can’t actually include pictures from the published paper, so instead I’ve substituted some of my other, less good images. Bear with me!

 

A little bit of BG

For anyone who isn’t aware, my Ph.D. thesis was about the taxonomy of British Jurassic pterosaurs i.e. testing species that have been described in the past and looking for evidence of new species. These aerial relatives of dinosaurs are well known to everyone, but what many don’t realise is how biased out understanding of them is. As discussed by Butler et al. (2009), pterosaurs studies have given a lot of attention to the latter third of the Mesozoic because of how much more material there was. This created a false impression that the Triassic and Jurassic were periods of slow development and diversification among pterosaurs. Recent discoveries however (Lu et al., 2010) have highlighted that the Jurassic may have been a far more dynamic period than previously believed. My thesis was based around this concept, with the major focus being looking at fossils collected in the 19th century in the light of what we know about pterosaurs today. One such specimen is GSM 3166, currently held in the British Geological Survey and the name-holder for the taxon Parapsicephalus (O’Sullivan and Martill, 2017).

 

A-head (I’m not sorry) of the game

Untitled-1

GSM 3166 as seen from the left.

GSM 3166 is a rare fossil, being one of the only Lower Jurassic (~182 ma) near-complete three-dimensional pterosaurs in the world. Recovered from the Whitby Mudstone Formation of Yorkshire It’s in good condition, missing only the rood of the skull, the tip of the jaw and the teeth. Not only that but it preserves a very nice endocast (i.e. a mould of the brain). It has suffered a bit over the years though, with the underside scoured in chisel marks and a lot of the bone on the side of the skull missing (which most likely occurred when the skull was removed from the rock). For such a great specimen though, it’d had a poor enough research record. Originally described by Newton (1888) as a new species of the German pterosaur Scaphognathus (Scaff-Og-Nay-Thus), it wasn’t looked at in any real detail until Arthaber (1919) examined it. He came to the conclusion that this skull was not from Scaphognathus but an entirely new pterosaur, which he named Parapsicephalus. Unfortunately, he didn’t provide a particularly detailed account, merely focusing on the downward curve of the skull. This is indeed an unusual feature and one he argued allied Parapsicephalus with another Lower Jurassic and fairly unusual pterosaur named Dimorphodon (Di-Morf-Oh-Don). The next major piece of Parapsicephalus research would show up in Kuhn (1967), who provided a modernised reconstruction of the skull. His reconstruction, later slightly modified by the famous Peter Wellnhofer, would serve as the basis for how Parapsicephalus was reconstructed in years to come. No one really paid much attention to Parapsicephalus after this until David Unwin, in his influential study into pterosaur family relationships (Unwin, 2003), had Parapsicephalus as an example of the German pterosaur Dorygnathus (Dor-Ig-Nay-Thus). This was a problem as the nature of this paper didn’t allow for an in-depth discussion as to why he placed Parapsicephalus in Dorygnathus. But from that point on, GSM 3166 was sometimes called Dorygnathus and sometimes called Parapsicephalus. Things got MORE confusing when Andres and Myers (2013) published their evolutionary tree, which agreed with Arthaber (1919), retained Parapsicephalus as a separate taxon and considered it to be most closely related to Dimorphodon. All of this was carried out without GSM 3166 receiving a good detailed description. So, during my Ph.D. I sat down, rolled up my sleeves, and tackled whether Parapsicephalus was valid in its own right or synonymous with another animal, and what were its closest relatives. I had a little help here as I got to examine a second Parapsicephalus skull from Altdorf in Germany, one that is currently in private hands but which showed up in the public eye in the later 90s.

 

Skull-duggery (I’m so punny)

GSM 3166 is an interesting bit of bone. It’s 140 mm long from the back of the skull to the break in the jaw, and it’s estimated that the complete skull was ~180 mm long. Unlike most pterosaur skulls it has a prominent dip, with the skull curving downwards between the top of the eye and the tip of the nose. By looking at the Altdorf skull, it becomes clear that this dip is natural but has become exaggerated over time. It also shows that the tip of the jaw curved upwards, probably meaning there was some slight splaying of the front most teeth. Speaking of teeth, the teeth in GSM 3166 are broken but we still have visible roots. These are evenly spaced, with three occupying the space between the eye and the antorbital fenestra (a hole in the skull found in animals commonly grouped together as the archosaurs i.e. crocodiles, pterosaurs and dinosaurs). The back of the skull is tall with an unusually deep jugal (cheek bone).

 

Insert head related pun here (yeah, I gave up trying)

r

From left to right: GSM 3166, Dimorphodon and Dorygnathus. The bone abbreviations aren’t relevant here but can be found in my paper, linked below.

So, the question is what can GSM 3166 be identified as? Is it a unique animal or just a synonym for Dorygnathus or Dimorphodon? Firstly, GSM 3166 can very quickly be separated from Dimorphodon. While there are a couple of minor similarities (the curved skull and the tall jugal), there are far more differences. GSM 3166 has fewer teeth than, a more angled back of the skull, the size and position of the skull openings is completely different, the jugal in GSM 3166 is actually THICKER than Dimorphodon, the list goes one. Previous identifications linking the two animals seem to have been mostly based on the exaggerated curve to the skull, but using the Altdorf skull it’s clear that in GSM 3166 the curve is not as strongly developed and changes into a fairly standard up turned front to the skull. There’s really very few similarities between the two. On the other hand, there is definitely more crossover with Dorygnathus (the general outline of the skull, number of teeth, relative size of the cranial openings etc). This doesn’t mean they can be synonymised however. GSM 3166 has a thicker jugal, a different shaped eye, the slight curve to the skull, a more developed upturn to the front of the skull, and several differences in the roof of the mouth (which I unfortunately don’t have great photos of). This combination of features, combined with the spacing of the teeth, mean that we can retain Parapasicephalus as a unique animal.

 

All in the family…head

So, I think we can say with some confidence that Parapsicephalus is its own thing. Does this mean we can be sure of its family? Nooooot so much. While we can confidently say it’s not closely related to Dimorphodon, where it falls is the pterosaur family tree is still a little up in the air. I identified it as most being related to Dorygnathus within the family Rhamphorhynchidae. However, a recent paper by Vidovic and Martill (2017) presents an evolutionary tree (properly referred to as a cladogram) which suggests that Parapsicephalus is perhaps more “advanced” than this, being closer to the derived late Jurassic Pterodactyloids. For the purposes of this research, it honestly doesn’t matter too much but it means there’s still a lot more we can learn about this animal. Get to it scientists!!!!

 

References:

Newton, Edwin Tulley. “On the skull, brain, and auditory organ of a new species of pterosaurian (Scaphognathus purdoni), from the Upper Lias near Whitby, Yorkshire.” Philosophical Transactions of the Royal Society of London. B 179 (1888): 503-537.

von Arthaber, Gustav. Studien über Flugsaurier auf grund der bearbeitung des Wiener exemplares von Dorygnathu Banthensis Theod. sp. In Kommission bei Alfred Hölder, Universitätsbuchhändler, 1919.

Kuhn, Oskar. Die fossile Wirbeltierklasse Pterosauria. Oeben, 1967.

Unwin, David M. “On the phylogeny and evolutionary history of pterosaurs.” Geological Society, London, Special Publications 217.1 (2003): 139-190.

Butler, Richard J., et al. “Estimating the effects of sampling biases on pterosaur diversity patterns: implications for hypotheses of bird/pterosaur competitive replacement.” Paleobiology 35.3 (2009): 432-446.

Lü, Junchang, et al. “Evidence for modular evolution in a long-tailed pterosaur with a pterodactyloid skull.” Proceedings of the Royal Society of London B: Biological Sciences 277.1680 (2010): 383-389.

Andres, Brian, and Timothy S. Myers. “Lone star pterosaurs.” Earth and Environmental Science Transactions of the Royal Society of Edinburgh 103.3-4 (2012): 383-398.

O’Sullivan, Michael, and David M. Martill. “The taxonomy and systematics of Parapsicephalus purdoni (Reptilia: Pterosauria) from the Lower Jurassic Whitby Mudstone Formation, Whitby, UK.” Historical Biology (2017): 1-10.

Vidovic, Steven U., and David M. Martill. “The taxonomy and phylogeny of Diopecephalus kochi (Wagner, 1837) and ‘Germanodactylus rhamphastinus’(Wagner, 1851).” Geological Society, London, Special Publications 455 (2017): SP455-12.

 

Advertisements

Leave a Reply

Fill in your details below or click an icon to log in:

WordPress.com Logo

You are commenting using your WordPress.com account. Log Out / Change )

Twitter picture

You are commenting using your Twitter account. Log Out / Change )

Facebook photo

You are commenting using your Facebook account. Log Out / Change )

Google+ photo

You are commenting using your Google+ account. Log Out / Change )

Connecting to %s