Labidosaurus hamatus
From Palaeos.org
This reconstruction is somewhat outdated but shows well the characteristics of the species.
The heavy ornamentation of the skull bones, a typical trait in larger captorhinids, is nicely depicted.
Labidosaurus hamatus is the largest among the single-rowed captorhinids and is known from a few skulls and numerous postcranial remains coming from the Lower Permian red beds of North Texas. It is currently the only recognized species of the genus Labidosaurus
Its skull measures about 20 cm in length. Given that the trunk length in Captorhinus is approximately 3.6-fold the skull length, the overall body length in L. hamatus was more than 90 cm. Another particularity concerning the skull is the large hook-like tip of the snout, formed by the premaxillary bone. Most of the captorhinids have such a down-curved premaxillary but in L. hamatus this feature is much more pronounced. Use and function of this toothed "beak" is as yet unclear. Some authors suggested it served as a tool for digging, but absence of characteristic scratch marks on the anterior teeth does not support this hypothesis.
The skull morphology places Labidosaurus close to the large multiple tooth-rowed captorhinids, the moradisaurines. Because herbivory is assumed for the latter the diet of L. hamatus may have included plants but its single rows of sharp conical teeth, rather suitable for piercing animal prey, suggests that it was most likely an omnivore.
The vertebral column of L. hamatus consists of 25 trunk vertebrae and at least 33 caudal vertebrae. There are two temporally and spatially coexisting morphotypes present in the vertebral column of Labidosaurus: one that has vertebrae with short neural spines and long such spines alternating and another that has exclusively vertebrae with short neural spines.
L. hamatus is one of the historically longest-known members of the family and was described as early as 1895 by one of the trailblazers of US-american vertebrate paleontology Edward D. Cope (albeit under a different name of genus). Some captorhinid fossils formerly referred to Labidosaurus are today assigned either to other captorhinid genera or to L. hamatus.
| †Labidosaurus hamatus Cope 1895 | |
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| Some Facts | |
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Family: Captorhinidae
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Stratigraphic Range: Lower Permian: Leonardian |
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References
CASE, E.C. (1911): A revision of the Cotylosauria of North America. Carnegie Institution of Washington Publication, vol. 145, Washington, D.C., 122 pp.
COPE, E.D. (1895): The Reptilian Order Cotylosauria. Proc. Am. Phil. Soc., 34(149), pp. 436-457
COPE, E.D. (1896): Second contribution to the history of the Cotylosauria. Proc. Am. Phil. Soc., 35(151), pp. 122-139
MODESTO, S.P., SCOTT, D.M., BERMAN, D.S., MÜLLER, J. and REISZ, R.R. (2007): The skull and the paleoecological significance of Labidosaurus hamatus, a captorhinid reptile from the Lower Permian of Texas. Zool. J. Linn. Soc., 149(2), pp. 237-262
SUMIDA, S.S. (1987): Two Different Vertebral Forms in the Axial Column of Labidosaurus (Captorhinomorpha: Captorhinidae). J. Paleontol., 61(1), pp. 155-167
Credits
--Zidane 10:45, 25 May 2008 (PDT)
