As the climate became drier, the early Permian semiaquatic and lowland floodplain Dimetrodon
and Eryops dominated fauna shown here, which had flourished for some 25 million years, was replaced by the more advanced floodplain and upland caesid and therapsid fauna.
From A.R. Milner, "Biogeography of Palaeozoic Tetrapods"
fig.13.3; in J.A. Long (ed.) Palaeozoic Vertebrate Biostratigraphy and
Biogeography, 1993, John Hopkins University Press, Baltimore
Edaphosaurid province
(equatorial Euramerica) |
Mesosaurid province
(south-west Gondwanaland) |
| Baigendzhinian |
10 |
277
278
279 |
Choza |
Hennesey |
|
|
|
|
|
| 9 |
Vale |
|
|
|
|
|
| 8 |
Arroyo |
Garber |
|
zone 0 |
|
|
|
| Aktasinian |
7 |
280
281
282
283 |
Ludens |
West Grandfield |
|
|
|
|
|
| 6 |
Clyde |
Deep Red Run |
|
|
Irati |
White band |
|
| 5 |
Belle Plains |
Wellington formation |
|
|
|
|
|
* approximate time in MYA (millions of years ago) - nearest
million year intervals
Xenacanthus
Length (total): about 1 to 2 meters
Diet: aquatic vertebrates
Comments:
Some Tetrapods - Aktasinian (Early Artinskian)
Eryops megacephalus [Cope]
Horizon: Wichita Series (Wolfcampian age), Texas Red Beds
Locality:
Specimens:
Length (skull):
Length (total): 1.5 to 2 meters
Weight: about 130 kg
Diet: other tetrapods
Comments: a large long-lived aquatic
temnospondyl
Arroyo Formation - Early Baigendzhinian Age
Dimetrodon
grandis (Case, 1907)
Horizon and Locality: Arroyo Formation, Clear Fork Group, Texas, USA
Specimens:
Length (skull): 42 cm
Length (total): 3.2 metres
Weight: around 250 kg
Diet: other tetrapods
Comments: The last and largest of the long-skulled, stocky-bodied lineage of
dimetrodonts. Apart from
D. angelensis this was the largest species of
Dimetrodon. A large, heavily-built, very common species, it is close to the earlier
D. limbatus, with which it differs in larger size, more elongate and stouter neural spines, and fewer premaxillary teeth (only two on
either side, the fewest for any species of the genus). It is associated with the slightly smaller but equally successful
Dimetrodon gigashomogenes
References: Romer and Price 1940,
Reisz 1986
Links:
Dimetrodon
gigashomogenes Case, 1907
Horizon and Locality: Arroyo, Vale and Choza Formations, Clear Fork Group, Texas, USA
Specimens:
Length (skull):
Length (total): 328 cm
Weight: around 166 kg
Diet: other tetrapods
Comments: A large representative of the short-skulled lineage of
dimetrodonts. Possibly ancestral to
D. angelensis. Although similar in size to
Dimetrodon grandis, it differs in the shape of the neural spines, the length of the vertebrae centra, and the lighter overall build.
D. gigashomogenes would seem to be a descendent, or possibly even the same species, of the
preceding
D. dollovanus, from which it differs mainly in larger size.
References: Romer and Price 1940,
Reisz 1986
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M. Alan Kazlev 2002
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checked ATW050514
(originally uploaded on Kheper Site 28 May 1998)
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Note: the following is based on Anderson and Cruikshank 1978 slightly modified.