In other words,
are the two erythrosuchid holotypes (Fig. 1) sufficiently alike to be congeneric or conspecific? Garjainia was published first.
Butler et al. 2019 reported
“Two species of Garjainia have been reported from Russia: the type species, Garjainia prima Ochev, 1958, and ‘Vjushkovia triplicostata’ von Huene, 1960, which has been referred to Garjainia as either congeneric (Garjainia triplicostata) or conspecific (G. prima).”
“…little work has been conducted on type or referred material attributed to ‘V. triplicostata’. However, this material includes well-preserved fossils representing all parts of the skeleton and comprises seven individuals. Here, we provide a comprehensive description and review of the cranial anatomy of material attributed to ‘V. triplicostata’, and draw comparisons with G. prima. We conclude that the two Russian taxa are indeed conspecific, and that minor differences between them result from a combination of preservation or intraspecific variation.”
Combining elements from seven specimens
bears some risk of creating a chimaera. Since Butler et al. felt confident in doing so, and there is no alternative, then I do, too. Given the data presented by Butler et al. I reconstructed the skull from separate elements (Fig. 1), something Butler et al. did not do.
Although the two skulls are extremely similar
and the two taxa nest together in the large reptile tree (LRT, 1602 taxa) a few traits seem to distinguish these two taxa apart from one another, at least at the species level and perhaps at the generic level. Note the larger antorbital fenestra in Vjushkovia. Note the pinched upper portion of the lateral temporal fenestra. Note the concave posterior maxilla. Note the taller, narrower orbit. Note the much more robust quadratojugal and quadrate. Note the greater arch of the posterior postorbital. Note the posterior process of the squamosal. These differences appear to support the separation of these taxa at the generic level, IMHO. The lack of a reconstruction in Butler et al. 2019 may have hampered their decision in this case. The lack of graphic comparison in the paper (no images of the Garjainia holotype are shown side-by-side with those of Vjushkoiva) is also regrettable.
Butler RJ, Sennikov AG, Dunne EM, Ezcurra MD, Hedrick BP, Maidment SCR, Meade LE, Raven TJ and Gower DJ 2019. Cranial anatomy and taxonomy of the erythrosuchid archosauriform ‘Vjushkovia triplicostata’ Huene, 1960, from the Early Triassic of European Russia. Royal Society Open Science 6: 191289. http://dx.doi.org/10.1098/rsos.191289
Criticisms of other papers by Butler as co-author: