Geikia
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Geikia Temporal range: Late Permian–Early Triassic |
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| Geikia and Sclerosaurus | |
| Scientific classification | |
| Kingdom: | Animalia |
| Phylum: | Chordata |
| Order: | Therapsida |
| Infraorder: | †Dicynodontia |
| Family: | †Geikiidae |
| Genus: |
†Geikia Newton, 1893 |
| Type species | |
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†G. elginensis Newton, 1893 |
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| Species | |
Geikia is an extinct genus of dicynodont therapsid from the late Permian – early Triassic. The abundance and diversity of dicynodonts during this period, combined with incomplete or inadequately prepared specimens, have led to challenges in determining relationships within this taxon. Only two species, Geikia locusticeps and Geikia elginensis have been assigned to this genus. While this is the currently accepted classification, fossil record limitations have led to repeated debate on the genus assignments of these species.
This genus was established in 1893 following Edwin Tulley Newton’s discovery of a new dicynodont fossil, now known as G. elginensis. Newton discovered this specimen in conjunction with other new reptiles, but believed that G. elginensis’ characteristics were sufficiently unique to justify a new genus. The holotype is the only known occurrence, and is housed at the Institute of Geological Sciences in London.
There have been two occurrences of the second species, G. locusticeps, both from the Ruhuhu Basin of Tanzania. Originally discovered by Friedrich von Huene in 1942, they are housed at the Institut und Museum für Geologie und Paläontologie der Universität Tübingen.
The name Geikia was proposed by E.T. Newton, who investigated the G. elginensis holotype in 1892. This name was a dedication to Sir Archibald Geikie, the Director-General of the Geological Survey at the time.
G. locusticeps was recognized as Dicynodon locusticeps until Timothy Rowe referred it to Geikia in 1980. It has been suggested that G. locusticeps may be a juvenile Pelanomodon tuberosus, and the two have been used synonymously. In 2005, it was proposed that P. tuberosus be referred to G. locusticeps as a junior subjunctive synonym.
Both belonging to the family Geikiidae, the genera Pelanomodon and Geikia are closely related. Morphological differences between G. elginensis and G. locusticeps, as well as individual similarities to other species (especially those within Pelanomodon) have been utilized in debates regarding their classifications. This exemplifies unresolved aspects of dicynodont taxonomy; it has even been suggested that single or incomplete dicynodont specimens should be considered incertae sedis until conclusions can be better ascertained through additional specimens or better preparation. More recent literature attributes the cross-genus similarities between Pelanomodon and Geikia to plesiomorphic Geikiid traits. With these considerations, it is currently maintained that the generic distinction of Geikia is warranted.
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Wikipedia