Saivodus striatus and the Graham formation Gilkmanius: Which one was bigger?

[Joseph Fossil]

The Ctenacanthiformes are an impressive group of prehistoric sharks, emerging in the Devonian period before surviving the two Devonian extinction events that gave rise to the Carboniferous. During the Carboniferous, the Ctenacanthiformes diversified rapidly, even becoming some of the Carboniferous Oceans Apex Predators. But of all the members of this impressive (yet almost unknown to the general public) group, two species stand out as especially impressive and awe inspiring - Saivodus striatus and the Graham formation Gilkmanius (this species currently doesn't have a name yet). 

 

Duffin, C. J., & Ginter, M. (2006). Comments on the Selachian genus Cladodus Agassiz, 1843. Journal of Vertebrate Paleontology, 26(2), 253–266. https://doi.org/10.1671/0272-4634(2006)26[253:cotsgc]2.0.co;2

 

Ivanov, A. O. (2005, September 1). The revision of "Cladodus" occidentalis, a late Palaeozoic ctenacanthiform shark. Acta Palaeontologica Polonica. Retrieved December 29, 2022, from https://www.academia.edu/49013029/The_revision_of_Cladodus_occidentalis_a_late_Palaeozoic_ctenacanthiform_shark

 

 

 

Artist reconstruction of the skeleton and size of the Graham formation (Upper Pennsylvanian, Carboniferous) Gilkmanius sp. By J. Maisey.

Image Source: https://www.amnh.org/explore/news-blogs/research-posts/ancient-supershark-fossils-found-in-texas

 

Maisey, J. G., Bronson, A. W., Williams, R. R., & McKinzie, M. (2017). A Pennsylvanian ‘supershark’ from Texas. Journal of Vertebrate Paleontology, 37(3). https://doi.org/10.1080/02724634.2017.1325369

 

 

 

Artist reconstruction of an Adult Saivodus striatus and its size compared to an adult Human and adult Great White Shark (Carcharodon carcharias) by artist HodariNundu.

Image Source: https://www.deviantart.com/hodarinundu/art/Super-Sized-Saivodus-866628428

 

 

Hodnett, J.-P. M., Tweet, J. S., & Santucci, V. L. (2022, August 8). The Occurrence of Fossil Cartilaginous Fishes (Chondrichthyes) within the Parks and Monuments of the National Park Service. researchgate.net. Retrieved December 30, 2022, from https://www.researchgate.net/publication/362806168_THE_OCCURRENCE_OF_FOSSIL_CARTILAGINOUS_FISHES_CHONDRICHTHYES_WITHIN_THE_PARKS_AND_MONUMENTS_OF_THE_NATIONAL_PARK_SERVICE

 

 

 

Both were giant members of the Ctenacanthiformes and were on par in size with the largest Great White Sharks (Carcharodon carcharias) (which can reach lengths of 20 feet). But the question I have is which species was bigger (in weight and in length)? Which one was the biggest of the Ctenacanthiformes?

 

@Elasmohunter @BobWill @connorp @deutscheben @jdp What do you think?

 

[BobWill]

Good question and we probably don't have the material you need to say for sure. The fragmentary portions of the brain case that was attributed to Saivodus striatus would be difficult to compare with what I found in the Finis Shale at Jacksboro. Since teeth are the most common fossils we have for making those comparisons and extrapolating size (and there is not total agreement on how that should work) we would need some pretty large ones from the Finis for that. I have a vague memory of Dr. Maisey saying that Mark McKinzie had found some very large teeth and there was some mention of teeth in the "Super Shark" paper but I don't believe there was a way to confirm the connection. As Dr. Maisey told me, "you need to go find the rest of that thing so we can give it a name." 

[jdp]

Good question but not one we have the data to answer. There might be ways of addressing some of these questions but there's gonna be a lot of uncertainty.

[Joseph Fossil]

23 hours ago, BobWill said:

Good question and we probably don't have the material you need to say for sure. The fragmentary portions of the brain case that was attributed to Saivodus striatus would be difficult to compare with what I found in the Finis Shale at Jacksboro. Since teeth are the most common fossils we have for making those comparisons and extrapolating size (and there is not total agreement on how that should work) we would need some pretty large ones from the Finis for that. I have a vague memory of Dr. Maisey saying that Mark McKinzie had found some very large teeth and there was some mention of teeth in the "Super Shark" paper but I don't believe there was a way to confirm the connection. As Dr. Maisey told me, "you need to go find the rest of that thing so we can give it a name." 

 

@BobWill Thanks Bob! I think it's super cool that you found the Graham formation shark braincase and donated it for the study. I emailed two of the scientists from the paper a while ago and yes, they did say that they saw potential "Gilkmanius" teeth measuring slightly more than 3 cm wide and 2 cm front to back (However, these specimens were not exactly cataloged so aren't in any museum collections yet). You are right though, more specimens are required to further clarify the matter on both the taxonomy and true size of the Pennsylvanian Graham formation "Super Shark".