Mr. Sanchez-villagra et al., Cranial anatomy and palaeobiology of the Miocene marsupial Hondalagus altiplanensis and a phylogeny of argyrolagids, PALAEONTOL, 43, 2000, pp. 287-301
New cranial material of Hondalagus altiplanensis, from the middle Miocene o
f southern Bolivia, allows a rediagnosis of the genus and an assessment of
its palaeobiology and phylogenetic relationships with other argyrolagid mar
supials. The new specimens demonstrate several derived (synapomorphic) cran
ial features shared by Hondalagus and Argyrolagus: a globular braincase, ve
ntrally directed occipital condyles, a broad zygomatic arch, and a short, d
eep dentary with a flat and long coronoid notch. Hondalagus had powerful ma
sticatory muscles and its cementum-encased hypselodont cheek teeth suggests
it had a very abrasive diet. The deep fossae on the lateral aspect of the
skull of argyrolagids, interpreted by Simpson as large, laterally-facing or
bits, are actually sharply margined temporal fossae. Hondalagus has a very
large carotid foramen medially situated within the suture of the basispheno
id and basioccipital. A phylogenetic analysis of five argyrolagid genera wa
s conducted using 32 characters (16 cranial, 16 dental) and a didelphid and
a caenolestid as outgroups. Hondalagus-Argyrolagus-Microtragulus form a mo
nophyletic group with an undescribed gen. et sp. nov. (MACN-Ch-1305) from t
he lower Miocene (Colhuehuapian) of Argentina as its sister taxon. Proargyr
olagus appears as sister group to the other taxa of argyrolagids.