Bryan Gee, Ph.D.
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Temno Talk: a blog about all things temnospondyl

New publication: Neurocranial anatomy of Seymouria from Richards Spur, Oklahoma (Bazzana, Gee, Bevitt & Reisz; JVP)

1/24/2020

 
Title: Neurocranial anatomy of Seymouria from Richards Spur, Oklahoma
​Authors: K.D. Bazzana, B.M. Gee, J.J. Bevitt, R.R. Reisz
Journal: Journal of Vertebrate Paleontology vol. 39(5), article e1694535
DOI to paper: 10.1080/02724634.2019.1694535
​
(email Kayla at kayla[dot]bazzana[at]mail[dot]utoronto[dot]ca if you don't have access or have questions, concerns, compliments, etc.)
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The goose of the temnospondyls: Chenoprosopus

1/21/2020

 
Geese are bastards, and this is an objective truth. I live in Canada, so I live with one of the biggest bastards of the geese family (it's family Anatidae if you're interested): the Canada Goose. It is rumoured that Canadians are so nice because the geese soak up all the mean vibes. I don't blog about geese or birds in general, but there is a temnospondyl out there whose name, for reasons entirely known to me, invokes the Greek root for 'goose' - up this week on the edopoid rotation is Chenoprosopus.

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Cochleosaurus, keeper of spoons

1/14/2020

 
Fresh off last week's blog on the "gluttonous face" Edops, we're hopping the pond and rolling into the "spoon lizard" Cochleosaurus! There is, unfortunately, no specimen with an anthropomorphic name as with "Grandpa Bumps," but what Cochleosaurus lacks in charismatic anthropomorphizing is made up for in the sweet, sweet sample size that includes a huge ontogenetic range, a rarity for Paleozoic temnospondyls.
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Photograph of a latex peel and corresponding illustration of a referred specimen of Cochleosaurus bohemicus (figure 1 from Sequeira, 2004).

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A new year of gluttony: Edops

1/7/2020

 
For the first #TemnospondylTuesday of 2020, I thought maybe I should kick off some themed month around the letter 'J' to get some of that alliteration going. The problem is that there is no group of temnospondyls whose name starts with 'J'; in fact, the only temnospondyl that comes to mind with a J-name is Jammerbergia, a capitosaur from the Early Triassic of South Africa. Nothing against Jammerbergia, but I don't have any particular connection to it, and it seemed kind of random to blog about it right now. So instead, I thought of the taxon perhaps most appropriate for those New Year's resolutions - Edops, whose name means 'gluttonous face!' That will probably lend itself for the theme of this month, as there are many other edopoids (unclear whether they were as gluttonous as the eponymous Edops​).
A brief history of study
Edops was named for the type species, Edops craigi​, by Romer (1936). The initial description is pretty brief and also in a journal that is very hard to come by (Problems of Paleontology). Following the publication of Edops, Romer set out to find more of this mysterious large temno in the redbeds of Texas, and basically hit jackpot that same year with a complete skull. Romer actually dubbed the specimen "Grandpa Bumps," and wrote a non-technical paper about the discovery of the specimen in 1943. It's probably worth noting that Romer intended the name to mean "swollen face," to refer to perceived, but as I understand it, the etymology does properly work out to "gluttonous face."
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Photograph of a cast of the most complete skull of Edops, "Grandpa Bumps" (figure 1 from Romer & Witter, 1942
"Grandpa Bumps" and other material was described by Romer & Witter (1942); this remains the most complete osteology of Edops to date. Based on this same material, Romer & Edinger (1942) provided the first endocast of the taxon. The stapes, among the largest of any known temnospondyl at 11 cm in length, has been described by Smithson (1982) as a comparison to the colosteid Greererpeton​ and recently by Schoch (2019) as a model for the plesiomorphic condition in temnospondyls. Edops craigi is the only known species, although material not attributed to this particular species has been reported outside of Texas from the Early Permian of Ohio (e.g., Olson, 1975), and something resembling Edops ​was reported from the Early Permian of New Mexico (Vaughn, 1969).
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Palate and mandibles of Edops craigi (figure 3 from Romer & Witter, 1942).
Anatomy
Other than Eryops, Edops is one of the largest terrestrial Paleozoic temnospondyls, with skulls exceeding half a metre in length and a body probably around 2 metres long. The name 'gluttonous face' refers to its large jaws, although it's a bit difficult to argue that they're appreciably larger than some other temnospondyls; as always, a healthy dose of salt is necessary. Compared to cochleosaurid edopoids, Edops does have a wider, more massively built skull. It is widely accepted to be a primitive temnospondyl based on features such as the presence of an intertemporal and small interpterygoid vacuities, with the pterygoid bones ('pt') meeting each other anterior to the vacuities. 

Edops also has a well-known neurocranium based on exceptionally detailed descriptions by Romer & Witter (1942) and the subsequent reconstruction of the endocast by Romer & Edinger (1942). The combination of their level of detail and the absence of substantial CT work on other temnos that often provides far superior detail to external anatomy for the braincase renders this still a very useful taxon for neurocranial anatomy in temnospondyls.
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Topology of temnospondyls from Schoch (2013). Red arrows mark Edopoidea and Edops.
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Braincase of Edops craigi in left lateral profile (anterior is to the left); most labels mark different openings for the 12 cranial nerves (figure 8 from Romer & Witter, 1942).
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Figure 5 from Romer & Edinger (1942).
Relationships
As I noted above, edopoids are typically recovered near or at the base of Temnospondyli; in the figure above on the left, you can see them as the earliest diverging clade over on the far left of the top phylogeny. Edops is not the earliest occurring edopoid, but it is usually recovered as the earliest diverging edopoid. Clearly this suggests that gluttony is plesiomorphic for temnospondyls...
Closing remarks
Although Edops is comparable to Eryops as far as size goes, it didn't last very long compared to its contemporaneous temno buddy, who has one of the most extensive stratigraphic ranges of any Paleozoic tetrapod. The type locality of Edops is in the Archer City Formation (probably earliest Permian), and its range extends down to the Markley Formation (probably latest Carboniferous). It's not entirely clear why Edops was less successful, but it was eventually replaced by the long-snouted cochleosaurid edopoid Chenoprosopus in North America. Perhaps the takeaway lesson here is that gluttony does not pay off in the long term, so stick to those New Year's resolutions!

Up next week: Cochleosaurus​

Refs
  • Olson EC. 1975. Vertebrates and the biostratigraphic position of the Dunkard; pp. 155-165 in Proceedings of the First IC White Memorial Symposium “The Age of the Dunkard."
  • Romer AS. 1936. Studies on American Permo-Carboniferous tetrapods. Problems of Paleontology, USSR 1: 85-93.
  • Romer AS. 1943. Hunting for Grandpa Bumps. The Scientific Monthly 57(1): 94-96. [permalink]
  • Romer AS, Edinger T. 1942. Endocranial casts and brains of living and fossil Amphibia. Journal of Comparative Neurology, 77(2): 355-389. doi: 10.1002/cne.900770203
  • ​Romer AS, Witter RV. 1942. Edops, a primitive rhachitomous amphibian from the Texas red beds. The Journal of Geology 50(8): 925-960. doi: 10.1086/625101
  • Schoch RR. 2013. The evolution of major temnospondyl clades: an inclusive phylogenetic analysis. Journal of Systematic Palaeontology, 11(6), pp.673-705. doi: 10.1080/14772019.2012.699006
  • Schoch RR. 2019. The stapes of Edops craigi and ear evolution in the lissamphibian stem group. Acta Zoologica 100(2): 126-134. doi: 10.1111/azo.12238
  • Smithson TR. 1982. The cranial morphology of Greererpeton burkemorani Romer (Amphibia: Temnospondyli). Zoological Journal of the Linnean Society 76(1): 29-90. doi: 10.1111/j.1096-3642.1982.tb01955.x
  • Vaughn PP. 1969. Early Permian vertebrates from southern New Mexico and their paleozoogeographic significance. Contributions in Science, Los Angeles County Museum of Natural History 166: 1-22. [link]

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