Geikia elginensis

Geikia is an extinct genus of dicynodont therapsids from the late Permian. 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.

A high level of skull specialization was significant in the classification of Geikia. Maisch and Gebauer considered the squared off anterior snout tip and reduced exposure of squamosal in occiput to be characteristics exclusively expressed in Geikia.

This genus was established in 1893 following Edwin Tulley Newton’s discovery of a new dicynodont fossil, now known as G. elginensis, one of the Elgin Reptiles found near Elgin in Scotland. 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 ...

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.

Compared to other dicynodonts, the shortened skull could be indicative of specific herbivory habits, such as biting off small pieces of vegetation. Pertaining to mastication, crushing action was likely more emphasized than slicing, due to structural limitations of lower jaw movement.

G. elginensis was discovered in the Cutties Hillock Sandstone Formation in Scotland. The coarse, hard sand presented difficulty in the development of the specimen, which was recovered from a pebbly layer near the base of the formation. The pebbles are characteristic of water deposition, suggesting a fluvial environment. Analyses have suggested that this formation is of Permian age, specifically Late Tatarian. Assuming accuracy of age assessment, this could be representative of offshore Zechstein.