Lambdopsalidae

Lambdopsalidae Temporal range: Thanetian/Late Paleocene
Lambdopsalis bulla - skull
Scientific classification
Kingdom:	Animalia
Phylum:	Chordata
Class:	Mammalia
Order:	†Multituberculata
Superfamily:	†Taeniolabidoidea
Family:	†Lambdopsalidae Chow and Qi, 19781
Genera
†Lambdopsalis †Sphenopsalis †Prionessus

Lambdopsalidae is a family of extinct multituberculate mammals from the Late Paleocene of Asia. They are part of Taeniolabidoidea, a clade otherwise present in the Early Paleocene (and possibly the Late Cretaceous) of North America. The Lambdopsalids probably evolved from a single radiation that spread into Asia from North America in the mid-Paleocene or earlier. They are represented by the genera Lambdopsalis, Sphenopsalis and Prionessus.²¹ This group was first defined in 1978 by Chow and Tao Qi.³

The Lambdopsalids were small mammals, with estimated adult body masses of about 0.4 kilograms (0.88 lb) to 0.8 kilograms (1.8 lb).⁴ They are notable for their enlarged teeth that implies adaptations towards leaf grazing,² and adaptations for burrowing such as a short and flat snout, robust humeri, stiff neck and enlarged lower incisors.⁵⁶ This group has a shared dental formula of 2.0.1.21.0.1.2³ Examples of Lambdopsalis are notable for offering direct evidence of hair and enamel and tooth prism patterns among multituberculates.⁷

Lambdopsalids lived during the Thanetian, the last stage of the Paleocene, with fossils ranging from 59-55 million years ago.⁸ They disappeared around the PETM.