SVP 2021 abstracts – 10: Apterodon taxonomic issues

Al Ashqar et al. continue:
“Here, we report the most complete Apterodon cranium ever recovered from Quarry M (~29
Ma), one of the youngest terrestrial localities in the Jebel Qatrani Formation of the Fayum Depression. Based on craniodental morphology, the new cranium is very similar to Apterodon macrognathus [Fig. 1] from Quarry A (~ 33 Ma), also in the Jebel Qatrani Formation.”

“The new skull preserves the complete upper left tooth row aside from I1 and P1 and right I2, P2-3 and M2. Like other apterodontines, the carnassial cutting blade is very reduced, reflecting a possible mesocarnivorous diet.”

That’s not a carnassial in Apterodon, it’s a molar. Purported sisters described by Al Ashqar are not related to one another in the LRT. He’s following a tradition based on taxon exclusion.

Al Ashqar et al. continue:
“The skull is anteroposteriorly elongate with a narrow, crushed rostrum. The nuchal crest and basicranium are well preserved with two large occipitals. The nuchal crest has a clover shape and does not reach the mastoid process. The neurocranium is complete and elongated. The zygomatic arches are dorsoventrally tall, broad and robust. The petrosal is preserved in the right side. The discovery of this cranium allows detailed craniodental comparisons with the better-known A. macrognathus, better documentation of the evolution of the distinct
apterodontine bauplan, and closer examination of the transtethyan dispersal of Apterodon during the Paleogene.”