Nine New Varanopseid (Eupelycosauria:  Varanopseidae) Specimens from the Richards Spur Dolese Brothers Quarry, Near Fort Sill, Oklahoma

By:  Andrea J.H. Doolan
For:  Dr. R.R. Reisz
Student #:  990145838
Course:  BIO481Y
Date:  2003/4/04

Hypothesis:  Unlike other locations where only one species of Varanopseidae (a pelycosaur mammal-like reptile family) is found, the fact that many different genera of varanopseids are found at the Dolese quarry in Oklahoma means something different is happens at this location.

Methods
Nine varanopseid specimens from the quarry
Compare them to a Mycterosaurus type specimen
Research the nature of the Dolese quarry

History of the Dolese Quarry:
10 km north of Fort Sill, Oklahoma
So far over 24 tetrapod specimens have been recovered from the quarry
Most prominent varanopseid found - Mycterosaurus
Consists of Ordovician Arbuckle limestone
30 m deep fissures developed in the Early Permian (290 million years ago)
Coarse conglomerates - fissure walls
Fine grey clays

Characteristics of Varanopseids:
Varanopseids are part of:
Amniotes (ancestors to all turtles, reptiles, mammals, and birds)
[picture]A phylogenetic tree of the amniotes. (After Reisz, 1997)
	Synapsids (a clade of basal amniotes; have one temporal fenestrae)
		"Eupelycosauria" (a group of basal synapsids; paraphyletic)
			Varanopseidae (a family of "eupelycosaurs")
[picture]Phylogenetic tree of the Varanopseidae. (After Reisz et al, 1998)

highly recurved, mediolaterally flattened teeth
specialised, gracile faunivores
long limbs and lightly built skeletons - active and agile lifestyle

Mycterosaurs Type Specimen (right maxillary fragment):
[picture]
compare all nine specimens to a Mycterosaurs type specimen (a varanopseid genus)
determine if the specimens belong to Mycterosaurus, or other genera of Varanopseidae

Subthecodont dentition
Highly recurved, mediolaterally flattened teeth
Cutting edge on the posterior margin of the teeth
Striations run from the tip of the tooth to the beginning of the bone of attachment
Maxilla itself is fairly flat, but exhibits a slight concavity

Specimen (PR 2072)
Differences between PR 2072 and the type specimen:
Serrations on both the anterior and posterior margin of the posterior tooth
Maxilla exhibited noticeable convexity
Anterior tooth in this specimen is quite large

Conclusions
None of the nine specimens belong to the genus Mycterosaurs
Each, however, does belong to Varanopseidae

This is a significant finding, because previously Mycterosaurus was the most widely known varanopseid found in the Dolese quarry.  This study suggests that many varanopseid genera in addition to Mycterosaurus might have dominated this landscape.  This study also adds to the taxa list found and described at Dolese, contributing to the overall species diversity.

The clay deposited in the fissures - formed by slow seepage
The conglomerates - formed by periodic floods

Therefore, there are several reasons why Dolese exhibits more than one varanopseid specimen, as well as other diverse taxa.  Once the fissures were filled with their clay and conglomerates, they would have been difficult to erode, which would have preserved the taxa encased within them.  Additionally, the arid setting surrounding Richards Spur appears to have been a good environment for varanopseids to survive and reproduce, perhaps suggesting why so many were preserved there.

References

Benton, M.J.  1997.  Vertebrate Paleontology.  Chapman and Hall.  pp 104-132.

Berman, D.S., and R.R. Reisz.  1982.  Annals of Carnegie Museum of Natural History 51: 423-453.

Everett, C.O.  1991.  An eryopid (Amphibia:  Labyrinthodontia) from the Fort Sill fissures, Lower Permian, Oklahoma.  Journal of Vertebrate Paleontology 11: 130-132.

Heaton, M.J., and R.R. Reisz.  1980.  A skeletal reconstruction of the Early Permian captorhinid reptile Eocaptorhinus laticeps (Williston).  Journal of Paleontology 54: 136-143.

Langston, W. Jr, and R.R. Reisz.  1981.  Aerosaurus wellesi, new species, a varanopseid mammal-like reptile (Synapsida:  Pelycosauria) from the Lower Permian of New Mexico.  Journal of Vertebrate Paleontology 1: 73-96

Reisz, R.R.  1997.  The origin and early evolutionary history of the amniotes.  TREE 12: 218-222.

Reisz, R.R., V. Barkas, and D. Scott.  2002.  A new Early Permian bolosaurid reptile from the Richards Spur Dolese Brothers quarry, near Fort Sill, Oklahoma.  Journal of Vertebrate Paleontology 22: 23-28.

Reisz, R.R., D.W. Dilkes, and D.S. Berman.  1998.  Anatomy and relationships of Elliotsmithia longiceps broom, a small synapsid (Eupelycosauria:  Varanopseidae) from the Late Permian of South Africa.  Journal of Vertebrate Paleontology 18: 602-611.

Reisz, R.R., and Sutherland, T.E.  2001.  A diadectid (Tetrapoda: Diadectomorhpha) from the Lower Permian fissure fills of the Dolese quarry, near Richards Spur, Oklahoma.  Annals of Carnegie Museum.  70:133-142.

Reisz, R.R., H. Wilson, and D. Scott.  Varanopseid synapsid skeletal elements from Richards Spur, a Lower Permian fissure fill near Fort Sill, Oklahoma.  Oklahoma Geology Notes 57: 160-170.

Sullivan, C., and R.R. Reisz.  1999.  First record of Seymouria (Vertebrata:  Seymouriamorpha) from Early Permian fissure fills at Richards Spur, Oklahoma.  Canadian Journal of Earth Sciences 36: 1257-1266.

Sullivan, C., R.R. Reisz, and W.J. May.  2000.  Large dissorophoid skeletal elements from the Lower Permian Richards Spur fissures, Oklahoma, and their paleoecological implications.  Journal of Vertebrate Paleontology 20: 456-461.