Any more information on the apparent Ctenacanthiform genus Pyknotylacanthus from the Early Triassic

[Joseph Fossil]

I've recently heard about a Ctenacanthiform genus named Pyknotylacanthus from the Triassic of what is now Nevada and Idaho. The Ctenacanthiform genus consists of two species (P. spathianus and P. humboldtensis).

 

 

What makes this genus so interesting is that while I've mostly heard that there is a gap in the fossil record between Permian and the Cretaceous where Ctenacanthiform fossils are recorded, this genus bridges that gap (if only by a little bit).

 

G. Guinot, et al. (2013). Cretaceous stem chondrichthyans survived the end-Permian mass extinction. Nature Communication. 4:2669 doi: 10.1038/ncomms3669

https://www.nature.com/articles/ncomms3669

 

P. Davidson (1919). A cestraciont spine from the Middle Triassic of Nevada. University of California Publications, Bulletin of the Department of Geology 11(4): 433-435

 

R. J. Mutter and H. Rieber. (2005). Pyknotylacanthus spathianus gen et sp nov, a new ctenacathoid from the Early Triassic of Bear Lake (Idaho, USA). Revista Brasileira de Paleontologia 8(2): 139-148

 

 

There is also more recently another unnamed Ctenacanthiform recorded from the Triassic Arrow Rock section of the Oruatemanu Formation of New Zealand (this record also somewhat bridges the Permian-Cretaceous gap in Ctenacanthiform records).

 

Grant-Mackie, & Yamakita, Satoshi & Matsumoto, & Hori, Rie & Takemura, & Aita, Yoshiaki & Takahashi, Satoshi & Campbell, Hamish. (2014). A probable shark dorsal fin spine fragment from the Early Triassic of the Arrow Rocks sequence, Whangaroa, northern New Zealand. New Zealand Journal of Geology and Geophysics. 57. 10.1080/00288306.2014.889722.

https://www.researchgate.net/publication/265606171_A_probable_shark_dorsal_fin_spine_fragment_from_the_Early_Triassic_of_the_Arrow_Rocks_sequence_Whangaroa_northern_New_Zealand

 

Iris Feichtinger, Andrea Engelbrecht, Alexander Lukeneder & Jürgen Kriwet (2020). New chondrichthyans characterised by cladodont-like tooth morphologies from the Early Cretaceous of Austria, with remarks on the microstructural diversity of enameloid, Historical Biology, 32:6, 823-836, DOI: 10.1080/08912963.2018.1539971

https://www.tandfonline.com/doi/abs/10.1080/08912963.2018.1539971?journalCode=ghbi20

 

 

 

What I'm really wondering is why has this Ctenacanthiform genus and it's confirmed presence in the Early Triassic been overlooked by most of the public (especially since the discovery of the Cretaceous Ctenacanthioform fossils in Europe in 2013 and 2020)?

 

 

 

[Joseph Fossil]

I'm also curious if anyone else has more info on the genus Pyknotylacanthus itself (the most recent paper I could find about the genus itself was from 2005)?

[jdp]

19 hours ago, Joseph Fossil said:

What makes this genus so interesting is that while I've mostly heard that there is a gap in the fossil record between Permian and the Cretaceous where Ctenacanthiform fossils are recorded, this genus bridges that gap (if only by a little bit).

 

I harp on this a lot, but there are shifts in sampling and in researcher effort following the early Permian. My understanding is that there are actually abundant ctenacanthiform spines and teeth in various parts of South America, for example, throughout the middle and upper Permian, but there just hasn't been the amount of work necessary to really get these described and identified. I would not be shocked if there are ctanacanthiforms in marine layers of the Triassic and Jurassic down there as well.