Cochilius

MacPhee, R. D. E., 2014, The Serrialis Bone, Interparietals, “ X ” Elements, Entotympanics, And The Composition Of The Notoungulate Caudal Cranium, Bulletin of the American Museum of Natural History 2014 (384), pp. 1-69 : 1-69

Cochilius (Interatherioidea, Interatheriidae , Interatheriinae)

and Relatives

Cochilius volvens , a moderately early member of the Interatheriidae , is represented in the comparative set by AMNH-VP 29651 from a locality “south of Lago Colhué-Huapí” ( Simpson, 1932b: 1), not otherwise identified. Structural details are well preserved at the microanatomical level, with few seriously fragmented areas (figs. 13–15). Other specimens examined: Cochilius volvens MLP 2339 (ex coll. Lillo).

2014 MACPHEE: NOTOUNGULATE CAUDAL CRANIUM 9

Protypotherium is common in Patagonian Santacrucian localities and thus well represented in museum collections. MLP 12-2780 is waterworn and partly encased in matrix; although damaged on exposed surfaces, scanning revealed that matrix-covered areas were quite intact. A mineral sinter, investing all surfaces, is particularly noticeable on trabeculae filling the epitympanic sinus; digital removal did not provide acceptable results, so images are presented as they appear in the original scans (figs. 16–17).

Other specimens examined: Interatherium (= Icochilius) extensum MACN 9738-39; Interatherium rodens MACN 9857-58.

Progaleopithecus tournoueri , which has a complicated taxonomic history, is of interest because it is part of a group standing as sister to Cochilius , Protypotherium , and Interatherium (see Hitz et al., 2006). Unfortunately, the only available specimen with a caudal cranium (AMNH-VP 29603) turned out on scanning to be much battered and figures little in this account.

Notopithecus adapinus AMNH-VP 28949 and 28673, representing the earliest conventionally recognized interatheriid subfamily (Notopithcinae), are very poorly preserved, although virtual sections of the skull were of some use in connection with gathering data on the presence of an entotympanic and septum bullae in notoungulates.