Asian gliriform origin for arctostylopid mammals

Area of Science:

• Paleontology
• Mammalian Evolution
• Biogeography

Background:

• Arctostylopids were historically grouped with South American Notoungulata due to dental similarities.
• Previous classifications were challenged by new dental and disputed tarsal evidence, leading to the proposed order Arctostylopida.
• Despite controversies, many researchers maintain the Arctostylopidae-Notoungulata link based on dental morphology.

Purpose of the Study:

• To identify and analyze tarsal morphology of Palaeostylops from the Late Palaeocene Subeng site in Inner Mongolia.
• To compare these tarsals with associated dental material from North American Arctostylops.
• To re-evaluate the phylogenetic affinities of Arctostylopidae.

Main Methods:

• Identification of Palaeostylops tarsals based on size and abundance at the Subeng site.
• Comparative analysis of identified tarsals with unpublished Arctostylops tarsals from a semi-articulated North American skeleton.
• Morphological comparison of arctostylopid tarsals with those of Pseudictops and Rhombomylus.

Main Results:

• Palaeostylops tarsals were identified in the Late Palaeocene Subeng fauna.
• Tarsal morphology of Arctostylopidae shows moderate similarity to Pseudictops and strong resemblance to Rhombomylus.
• The findings support grouping Arctostylopidae with Asian non-gliroid Gliriformes.

Conclusions:

• Arctostylopidae are re-associated with Asian Gliriformes based on tarsal morphology.
• This reclassification suggests a dispersal of Arctostylopidae from Asia to North America during the Late Palaeocene.
• The study resolves long-standing debates regarding the phylogenetic position of Arctostylopidae.