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Kem Kem Notosuchian or Theropod?


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PointyKnight

Hey everyone!

 

I just received a few teeth from the Kem Kem Beds near Taouz, Morocco. Among them one has me particularly stumped - I’ll do my best to provide as much information as possible, but let me know if more is needed!

 

Mystery.thumb.png.01ae1d50ab882af1c5466a73c769c8f5.png

 

The tooth was listed as a theropod, though even the seller thought that assignment was only tentative. Its total height is 14mm. As the pictures above show, it’s moderately recurved as well as slightly curved lingually, with very distinct flutes running the whole length of the crown, 6 lingually and 9 labially, with the lingual flutes appearing stronger. It’s mediolaterally compressed, with a flat (or slightly concave?) lingual and more rounded labial profile, and a slightly lingually offset mesial carina. The distal carina reaches the base of the crown, whereas the mesial carina stops slightly short of it. The serration density on the distal carina is about 5/mm, on the mesial carina it’s about 7.5/mm (definitely noticeably smaller), getting more dense towards the base.

 

When it comes to weird carnivores there’s of course no shortage in the Kem Kem, with a plethora of unusual teeth without a known owner. So far I haven’t come across one quite like this. I wouldn’t want to exclude the possibility of it being a theropod completely from the start. Still, my first thought went to Notosuchia:

 

There’s an abundance of notosuchians known from the Kem Kem Group, probably as many described as undescribed. For one, there’s the small uruguaysuchid Araripesuchus rattoides (SERENO & LARSSON 2009), which can be excluded pretty easily. Aside from A. rattoides teeth being generally far smaller, the morphology doesn’t fit either: Specimens such as MNN GAD19 illustrate well that the largest teeth in Araripesuchus, its caniniforms, are recurved, but far more bulbous than what we are looking for. The other parts of its dentition are highly heterodont, with mostly small, low, rounded crowns. Additionally, none of its teeth are fluted in the fashion we see here.

 

Next in line are the peirosaurids Hamadasuchus rebouli (BUFFETAUT 1994) and an as of yet undescribed taxon likely closer to more derived peirosaurids, Peirosauridae B [ROM 52620 and ROM 49282]. The latter is often attributed to H. rebouli, but will hopefully be revised after the description of BSPG 2005 I 83. IBRAHIM et al. 2020 lump everything into Hamadasuchus, but didn’t do their own analysis and note that reevaluations are in order. Similar to Araripesuchus, peirosaurids are highly heterodont, with conical anterior teeth and lower, more robust posterior teeth. The relatively high number of specimens helps in this regard: While recurved, the anterior teeth in Hamadasuchus are subconical and not overtly fluted. The posterior teeth, while possessing serrated carinae and showing some fluting, are far more stout and bulbous. In Peirosaurid B, the anterior teeth, most notably the caniniforms, are indeed fluted and recurved, but are very conical and do not possess serrated carinae. The posterior teeth, while possessing serrated carinae, some mediolateral compression, and being overall taller than in Hamadasuchus, are not recurved or fluted, but symmetrical and far more blunt than the pointed form we are looking for.

 

Lastly, there are the ziphosuchians: IBRAHIM et al. 2020 use ‘Candidodontidae’ CARVALHO et al. 2004, though they note it’s unclear what exactly this family comprises of, so it might be best to treat its members simply as basal ziphosuchians. Libycosuchus brevirostris (STROMER 1914, 1915) has very little preserved in terms of teeth, and sits between other notosuchians which have very strange dentitions themselves. Looking at relatives such as Candidodon (CARVALHO & CAMPOS 1988), it would appear that these basal taxa would also have had mostly heterodont dentitions with conical anterior and low posterior teeth. Additionally, BUFFETAUT 1976 notes that the teeth appear to have been comparatively small overall, which appears right when looking at the alveoli of BSP 1912. I couldn’t find any reference to fluting or serrations in its immediate relatives, only in the far more derived members of this group, called ‘advanced notosuchians’ by POL & LEARDI 2015. There’s some evidence that animals similar to these younger South American taxa might have existed in the Kem Kem noted by IBRAHIM et al. 2020, but even then, the anterior teeth in this group show a consistently conical or teardrop-shaped cross-section, not the compressed shape we see here. IBRAHIM et al. 2020 go on to refer some material to Sebecidae SIMPSON 1937, though this is likely due to the general instability in notosuchian taxonomy. The material isn’t described in the text, but is highly doubtful to be from a true sebecid, as that family is only known from the Maastrichtian onward.

 

Quite frankly I’m at a bit of a loss. I know trying to ID Kem Kem teeth too often ends in ‘We just don’t know’, and having looked at the options I haven’t made much headway - the tooth doesn’t really resemble anything that’s described or goes into the direction of what’s undescribed and fragmentary, at least to me. So I’d like to hear your opinions - is there something I have grossly overlooked? Is it just a very weird notosuchian or something else? Could it be a theropod after all? I’d love to hear your thoughts!

 

Thank you very much for your help!

 

 

BUFFETAUT, E. 1976: Der Land-Krokodilier Libycosuchus STROMER und die Familie Libycosuchidae (Crocodylia, Mesosuchia) aus der Kreide Afrikas

BUFFETAUT, E. 1994: A New Crocodilian from the Cretaceous of Southern Morocco

CARVALHO, I.d.S., & CAMPOS, D.d.A. 1988: Um mamífero triconodonte do Cretáceo Inferior do Maranhão, Brasil

CARVALHO, I.S., RIBEIRO, L.C.S. & AVILLA, L.S. 2004: Uberabasuchus terrificus sp.nov., a New Crocodylomorpha from the Bauru Basin (Upper Cretaceous), Brazil

IBRAHIM andabunchofothers, 2020: Geology and Paleontology of the Upper Cretaceous Kem Kem Group of Eastern Morocco

POL, D. & LEARDI, J.M. 2015: Diversity Patterns of Notosuchia (Crocodyliformes, Mesoeucrocodylia) During the Cretaceous of Gondwana

SERENO, P.C. & LARSSON, H.C.E. 2009: Cretaceous Crocodyliforms from the Sahara

SIMPSON, G.G. 1937: New Reptiles from the Eocene of South America

STROMER, E. 1914: Ergebnisse der Forschungsreisen Prof. E. Stromers in den Wüsten Ägyptens. II. Wirbeltier-Reste der Baharije-Stufe (unterstes Cenoman). 1. Einleitung und 2. Libycosuchus

 

@Troodon

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pachy-pleuro-whatnot-odon
Posted (edited)

Unfortunately, all I say is that this isn't Hamadasuchus rebouli. But it does look crocodilian to me too...

 

Some H. rebouli teeth for comparison (or at least what passes for it on the market anyway):

1309699881_.31_Hamadasuchus_tooth_02.jpg.71c7c1b8e57a186ffcc0c818e71fe64c.jpg

624114755_Hamadasuchus_0.43_tooth_03.thumb.jpg.7d2f8cbd7e7d451a42a4f534fd7156d1.jpg

276432136_PartiallyrootedHamadasuchusrebouli1.1tooth02.thumb.jpg.73a6906776dd179cd0734434ad9c7814.jpg

2035971758_rootedhamadasuchusreboulitooth01.thumb.jpg.60dc0799ee77e700640f817c7bfe83e1.jpg

Edited by pachy-pleuro-whatnot-odon
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Omnomosaurus
Posted (edited)

Ah, so you're the one who bought this tooth! It's definitely an unusual one.

 

There are a few interesting features, but I'd personally say your tooth lies more toward the crocodylomorph side of things....not that my opinion counts for much, haha.

 

Some of the features remind me of this probable indeterminate croc tooth I have. I had originally floated the idea of it possibly being from a juvenile Spinosaurid, but that's pretty unlikely.

 

Though yours is more compressed and more recurved, the serrated carinae, shorter mesial carina, fluting and strong apex are quite reminiscent.

 

IMG_20210609_214806851.thumb.jpg.84c2e3ee4b52b15d2b6f383733e32733.jpgIMG_20210609_215102982.thumb.jpg.975c46d773201db8f460609b0e525b23.jpg

 

(Excuse those photos, I just quickly picked up the tooth and snapped a couple of shots without the proper setup.)

 

Edited by Omnomosaurus
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Troodon

I lean toward being a indeterminate Crocodyliform tooth,  it's not theropod.  There is a diverse array of Crocodyliforms in the KK Group most with incomplete dentitions so lots of unknowns.  I think Ibrahim et al  2020 paper does the best job to summarize the current view.

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Haravex

I'm working with someone currently who found some exceptionally large serrated crocodile teeth (over 1 inch) which excludes the current known serrated tooth crocodiles such as hamadasuchus.

For now is best labeled as crocodylomorph indet (and keep a hold of it)

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PointyKnight

Thanks for your input everyone!

 

@pachy-pleuro-whatnot-odon That’s the big problem, these various morphotypes of notosuchian teeth have a tendency to blend into each other - ‘Araripesuchuswegeneri is from the Aptian-Albian of Niger, so a bit too old unfortunately. Interestingly, it’s no longer considered a species of Araripesuchus, but a new genus for it is yet to be erected.

 

@Omnomosaurus Haha, yeah it was! I’m definitely settled on crocodyliform by now, thanks to @Troodon for confirming it, too! Your tooth has all the characteristics of an anterior Elosuchus tooth: They’re robust, roughly conical, lingually recurved, bicarinate, serrated, and commonly exhibit fluting. Supposedly, there’s a second large tethysuchian in the Kem Kem that has been teased for a few years now, but it might very well end up being Elosuchus, too.

 

@Haravex That sounds really interesting! Certainly there’s a lot left undiscovered - before diving deeper into the subject I wasn’t aware of just how huge Hamadasuchus could get, but looking at specimens like the holotype PV R 36874, its skull would have approached 60cm in length, with caniniforms around 2 inches long! It’s certainly exciting what other terrestrial crocs we might be seeing from this place in the future!

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