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Tuesday Tetrapod (1 of 2): Fishapod?

Posted by tigerhawkvok on July 28, 2009 17:27 in paleontology , tuesday tetrapod

For today's first Tuesday Tetrapod, I present ... an unidentified "fishapod" fossil.

Fossil

Basal tetrapod (?) fossil find.

Fossil anterior portion

Anterior portion of the fossil. Penny for scale.

Fossil posterior portion

Posterior portion of the fossil.

Whole fossil, rotated

This find was located by Sara's aunt and uncle (though I won't disclose the location — things are in process to get it into the proper hands for museum care). Since this is unidentified, it'll be a walk through the features we can currently see in the rock — though it is actually not wholly clear if it is actually a tetrapod yet (via discussions with UCMP contacts)!

So, here are some nifty features I think that lend toward identification as a basal tetrapod, or what is sometimes jokingly called a "fishapod":

Ribs on fossil tail

Note the ribs on the fossil tail. These are commonly found on animals with fleshy tails used for swimming.

  • Looking at the anterior portion of the fossil, there are obvious ribs along the caudal vertebrae. While these are apparently in the transverse direction, they could easily just be distortion from the process of fossilization.
  • There are structures adjacent to a large mass on the posterior half of the animal. While not quite clear in the photographs, it seems to be fairly robust and narrow element, and possibly two other connected elements near the midline. I postulate that these could be the pelvic girdle, femur, and a fibia/tibula
  • The pelvic structure appears mirrored across the vertebral column, though perhaps not strongly joined, indicated a basal state.
Fossil pelvic girdle

Region around the presumed pelvic girdle of the fossil. Light outline is one hypothesized articulation for the detached bone.

Finally, the anterior portion of the fossil has a well developed jaw that appears not exceptionally "fish-like" and more like early tetrapods. In addition, the cervical vertebrae have well-developed bones by them (processes?) that could be hyoid bones / remnants of gill arches, and well-developed hyoids are also seen in modern amphibians for feeding — though this part of my analysis is admittedly more sketchy, as I am not up on my fish anatomy.

So perhaps this entry is a week late -- but hopefully it was worth the wait!

Please note that all photos in this blog post were taken by Sara Weinstein, and copyright (or copyleft or any other form of release) belongs wholly to her. Please visit her blog and drop her a line there if you'd like to use the photos!


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freedom mentor

freedom mentor | 27/02/2015 18:32

Tuesday Tetrapod (1 of 2): Fishapod? | The Dichotomous Trekkie 2.0

freedom mentor

freedom mentor | 27/02/2015 18:29

Tuesday Tetrapod (1 of 2): Fishapod? | The Dichotomous Trekkie 2.0

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http://y175540.51host.net/ | 09/02/2015 13:41

Tuesday Tetrapod (1 of 2): Fishapod? | The Dichotomous Trekkie 2.0