A Trio of Temnospondyls
11:32 pm
About a week ago, the Geological Society of America announced the discovery of an unique trace fossil from the Mississippian-age Mauch Chunk Formation in eastern Pennsylvania, which preserved the impressions of three temnospondyl amphibians that laid in this Mississippian mud some 330-million years ago.
Photo credit: Spencer G. Lucas,
New Mexico Museum of Natural History and Science
Spencer G. Lucas (New Mexico Museum of Natural History and Science), David L. Fillmore and Edward L. Simpson (both from Kutztown University in northeastern Pennsylvania) presented this unique fossil at the 2007 GSA Annual Meeting. Spencer asked me to draw up a reconstruction showing the temnospondyls whose imprints were preserved in the fossil, which I took particular pride in, since I, too, happen to be a tetrapod from eastern Pennsylvania. My take on the temnospondyl trio is shown below:
My take on the temnospondyl trio. The impressions in the fossil slab are raised, so when you look at it you are
actually seeing the animals’ imprints from underneath; in this top-down view their positions are flipped horizontally.
This drawing was included in the press release but, due to a miscommunication, it was not initially credited. Oddly enough, I was back in northeast PA visiting family when the release went out, so I didn’t realize it until I returned to New Mexico yesterday. I’m happy to say that the oversight has since been corrected on the GSA page.
But beyond my personal stake in the story, the fossil really is quite spectacular. The imprints seem to show your standard temnospondyl four-fingered hand, and what looks like a crease of skin down the midline of their bellies, with no apparent sign of scales. As Lucas et al. note in their abstract, the fact that the three were preserved together indicates some sort of gregarious activity, and the tastefully phrased “head-to-tail overlap” shown in two of the impressions is reminiscent of the courtship behaviors of some modern amphibians.
I hadn’t even noticed that there was more than one individual represented – this is even neater than I thought.
This is a great drawing, Matt. Are temnospondyls related to any living amphibian groups, or were they dead ends? They look like salamanders, but I think salamanders probably represent more of a basal tetrapod body type than anything else…
Some researchers have suggested that modern amphibians have their roots in the temnospondyls (and I think Palaeos might reflect this view), but I think they are now mostly considered to be a dead end. The Tree of Life has a good summary of temnospondyl relationships.
I saw the poster and I thought the style looked familiar. Awesome find, and awesome reconstruction!