Another annoying zoological specimen that needs identifying

This incomplete fossil skull was collected from the coast of northern Africa by Dave Martill and is suspected to represent a new species. It's one of those annoying back-burner projects that sits there on your desk for months and months.. eventually the months turn into years and still have you haven't gotten round to dealing with it.. Anyway, work on it is far from complete but I've had a go at identifying it. Who wants to try their luck © and have a go at doing likewise...

i-5119e228c3de58aa7c44e5d683e7f230-left lat and dorsal composite 22-8-2008 resized.jpg

In the composite here, it's shown in left lateral and dorsal view. Note the ruler...

Here it is in palatal view, showing the alveoli...

i-3549e216a7cc0cbc3e4fc21aa30992b9-palatal view resized 22-7-2008.jpg

Well? Incidentally, this isn't the first 'mystery' specimen that I've put up for identification at Tet Zoo (and I mean proper mystery specimens: not ones where I definitely know the answer). The others are the frasercot skin, McGowan's mystery bovid, and the weird rug-like mammal skin I never got round to elaborating on. I must do a follow-up on all of those specimens some time.

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We looked previously at a partial skull, collected in northern Africa. Apart from the odd outing when it's been used in teaching, it's been sat in a box on my desk for a couple of years now, forlornly hoping that it might one day earn a place in the peer-reviewed literature. However, that would…

Looks like some sort of whale skull doesn't it? Some kind of large dolphin perhaps?

By Dave Godfrey (not verified) on 22 Jul 2008 #permalink

It's clearly a dolphin/porpoise skull - although it is rather small. Perhaps a juvenile? The poor state of preservation doesn't much help with indentification.

No, not frexhwater dolphin...
...He said it was a fossil...a arcoceti?

tursiops spp. ... or driftwood ?

It certainly doesn't look like a fossil, per say, but that glyptodont didn't look like a fossil, either. It's either a dolphin or that toothed whale that also has evidence of baleen.

I'm not claiming I came to this conclusion through any sort of expertise, but rather a complete guess based on nothing but the general shape and the size (everyone else thinks its a dolphin too).

A Hector's Dolphin?

I will conclude that it is the skull of the long nosed aquatic gorgonopsian _Thalassogorgon_. This identification is supported by the terrifying strength of the crepuscular fascule and by the enlarged and vehement prominence of the nasolabious glabellum.

Or it could be a busted dolphin skull.

By Hubert J. Wick… (not verified) on 22 Jul 2008 #permalink

Thalassogorgon? Oh please. This thing clearly has many impressive teeth and a small brain. It's obviously an Ambulochaser, the dreaded Oceanic Trial Attorney.

The first thing that occurred to me was some sort of cetacean, too (and then a dolphin when I glanced at the ruler), but I thought maybe that was just the wishful thinking of my inner marine biologist. But seeing as everyone else has come to the same conclusion...

My first reaction was dolphin, theres a few similar skullas at the NHM. In fact it has a vague resembalance of a narwhal skull in the second photo but I think thats the ways its broken

I obviously need a refressher course on cetacean osteology: I was going to say "Mysticete" when I could only see the dorsal and lateral views, but then there were all those tooth sockets in the palatal view!
Sorry, all I can do is confess amateur standing!

By Allen Hazen (not verified) on 22 Jul 2008 #permalink

I'll make a more educated, more precise ID later, but this skull is a dead ringer for a delphinid. It looks very much like Tursiops, but there are several other genera of generalized delphinids that it could be as well.

You guys are getting fooled by the supposedly cetacean appearance. Haven't you all heard of the recently discovered (and sadly also recently extinct) aquatic ropen Thaumatoropenis thalassina! It was a late-surviving pterosaur that descended from the marine ropens. These actually took to the oceans in the Paleocene and converged with cetaceans in terms of lifestyle. Not only did they become marine predators, they converged with cetaceans in terms of cranial features and even virtually lost their hindlimbs, while their tails grew and evolved flukes like those of ichthyosaurs. Unfortunately, it seems that they were endemic to the ancient Tethys, and when that closed up due to plate tectonics, they died out. But before that happened, a single lineage had actually returned to the land, colonised Africa, and re-evolved flight. Thaumatoropenis is actually the last surviving species, observations have recorded it as finding food by skimming, combined with walking on the ground and picking off small creatures. Unfortunately, this skull is all that is left of it; the rest of the specimen was torn apart by a gang of apparently giant black domestic cats. There are reports of a second species, the Kongomatu, but despite repeated expeditions by the famed Dutch biologist Marc van Nistelrooy (who has discovered many new species) into the Congo, a specimen has not been obtained yet.

Did I really have to tell you all that? Sheesh, this was all in the news in April. Darren's just been too busy to blog about it, that's all. I thought you guys would have been more up to date. *shakes head*

Okay, in all seriousness... squalodontid? I have no idea myself.



Not that I could be of any help, but it clearly is a dolphin. How many species of dolphins are there? 200?

By David Marjanović (not verified) on 22 Jul 2008 #permalink

Oh. Squalodontid... squalodontids were stem-odontocetes, right?

I revise my diagnosis, unfortunately in the wrong direction: it's an odontocete, but neither a sperm whale nor a beaked whale.

Is it actually an odontocete...?

By David Marjanović (not verified) on 22 Jul 2008 #permalink

Before seeing the palatal view below the fold I thought it was a pigmy rorqual. Clearly not, then. Squalodontids I would expect (without checking) to have 2-rooted cheek teeth (quick Google confirms this). The various narrow-snouted river dolphins can be ruled out, along with all the forms with reduced dentitions, anteriorly flaring crests around the melon, etc. Something not too far from bottlenose Tursiops, or melon-headed whale Peponocephala. Too many Recent species!

By John Scanlon FCD (not verified) on 22 Jul 2008 #permalink

Just from the prominent difference in the last five teeth sockets I am thinking maybe related to the Amazon river dolphin.

Missisippi river dolphin?

I can state with dead certainty that this is not a boneless aquatic pterosaur, and I believe I have reason for great confidence in my judgment that it is not a scansorial plesiosaurid either.

By Nathan Myers (not verified) on 22 Jul 2008 #permalink

I was going to say dolphin, but everyone else beat me to it.

It's either that or a late-surviving marine snouter.

David... Its definitely not a squalodontid. Squalodontids had extremely long rostra with procumbent, caniniform incisors.

This skull is fairly young, and definitely represents a delphinid (i.e. it can be firmly excluded from other delphinoid groups such as the phocoenidae [porpoises], monodontidae [beluga and narwhal], physeterids [sperm whales], ziphiids [beaked whales], stem odontocetes, and platanistoids ["river dolphins" and squalodontids, and several other weird groups).

I'm gonna stick with my ID of Tursiops... although with the exception of globicephaline delphinids, there aren't a whole lot of discrete morphological differences among delphinids with the exception of cranial proportions; delphinids are a very hard group to study due to their diversity, and the fact that many of the various species hybridize, quite extensively.

Additionally, here are some delphinid genera that it can be confidently excluded from: Stenella, Delphinus, Steno, Feresa, Globicephala, Orcaella, Orcinus, Pseudorca, Grampus, Lagenodelphis, Lissodelphis, Sotalia...

That pretty much leaves Tursiops, Lagenorhynchus, and two I don't have photos of - Sousa and Cephalorhynchus. The skull has a very strong postorbital process, and a steeper vertex, as opposed to Lagenorhynchus and similar to Tursiops. Additionally, Lagenorhynchus has about 10 more teeth than the unidentified specimen.

OK, finally got a picture of a skull of Sousa and Cephalorhynchus, and its definitely not it.

Cephalorhynchus is pretty tiny, has 28 teeth minimum, and the rostrum is much different in lateral/dorsal view. I'm sticking with my identification of Tursiops, due to the large size, robust rostrum, low tooth count, steep vertex, and the large postorbital process.

I'm also going to venture a (somewhat wild) guess that this specimen is Plio-Pleistocene in age.

I will say dolphin or porpoise, with my abysmal knowledge of osteology.

Or maybe squashed flat Deinocheirus, which, as we now learned, climbed trees and hunted like drop bear.

Evidently it's some form of White Whale. Hand me my Harpoon!

By Graeme Elliott (not verified) on 23 Jul 2008 #permalink

I thought dolphin. Seeing all the knowledgeable folks saying the same thing, I get this sinking feeling we've somehow walked into a trap ...

By Andreas Johansson (not verified) on 23 Jul 2008 #permalink

It seems to bee the skull of the Rough-toothed Dolphin (Steno bredanensis) for the numer of teeth and the shape of the skull...

By Alessio C. (not verified) on 23 Jul 2008 #permalink

Naw, its not Steno. Steno has a really long, narrow rostrum, like Delphinus and Stenella. Steno also has the dorsal margin of its orbit higher (dorsally speaking) than the top of the rostrum.

You are right! Then probably it's Tursiops truncatus...

By Alessio C. (not verified) on 23 Jul 2008 #permalink

People, please. It is so obviously not a dolphin.

It is, at best, half of a dolphin. Hemitursiops, perhaps? Definitely the left-handed morph, whichever hemitaxon it represents.

Remind me to show you my awesome collection of Vertebrasaurus acraniata sometime. They're filed with my exhaustive photo-journal of doughnut holes.

Also, I am contractually obligated to suggest that the thing in the picture might be a thalassic hellathere.

I guess I'll throw my lack of knowledge hat into the ring. I'd say it's either an electra dolphin (peponocephala electra) or a lagenodelphis, more likely the former. Although it doesn't seem to have enough teeth for either. Maybe it's one of those weird hybrid dolphins like a wolphin or something.

Nothing to add here, except that it is clearly a dolphin (even though I know very little about specific bone features, dolphins are the only mammals I can think of with tooth-rows like that)
I do want to say though I love these little challenges. So interesting to the scientific part of my mind. You guys don't know it, but you're all really giving me a great post-secondary education. Thanks.

By Max Paddington (not verified) on 23 Jul 2008 #permalink

A friend who knows more about whales than I says:

"It's not a fossil, it's a beat-up beach specimen of Tursiops.

- bleached white bone, abraided by wind-blown sand, fragmented and missing its teeth

- slight rise of the premax in lateral view along the rostrum and then the abrupt rise of premax posteriorly near vertex

- big honkin' orbits, almost like Orcinus in relative robusticity"

I think I'm going to agree with the last poster. It's a Tusiops. I thought maybe the beak was too short but then I looked at some photos of Tursiops skulls and it seems about right. The number of teeth seem to fit better too then with my orginal guess of an electra dolphin too. The problem is there is too much of the skull missing to really tell. (Like those big honkin' orbits for example...Don't most dolphin species have relatively large orbits?)