Arboroharamiya: What a Single Fossil Can do to a Nice "Neat" Phylogeny

A new arboreal haramiyid shows the diversity of crown mammals in the Jurassic period

Authors:

1. Xiaoting Zheng (a,b)

2. Shundong Bi (c,d)

3. Xiaoli Wang (a,b_

4. Jin Meng (c,e)

Affiliations:

a. Institute of Geology and Paleontology, Linyi University, Shuangling Road, Linyi City, Shandong 276005, China

b. Shandong Tianyu Museum of Nature, Pingyi, Shandong 273300, China

c. Key Laboratory of Vertebrate Evolution and Human Origin of Chinese Academy of Sciences, Institute of Vertebrate Paleontology and Paleoanthropology, Chinese Academy of Sciences, Beijing 100044, China

d. Department of Biology, Indiana University of Pennsylvania, Indiana, Pennsylvania 15705, USA

e. Division of Paleontology, American Museum of Natural History, Central Park West and 79th Street, New York, New York 10024, USA

Abstract:

A major unsolved problem in mammalian evolution is the origin of Allotheria, including Multituberculata and Haramiyida. Multituberculates are the most diverse and best known Mesozoic era mammals and ecologically resemble rodents, but haramiyids are known mainly from isolated teeth, hampering our search for their phylogenetic relationships. Here we report a new haramiyid from the Jurassic period of China, which is, to our knowledge the largest reported so far. It has a novel dentition, a mandible resembling advanced multituberculates and postcranial features adapted for arboreal life. Our phylogenetic analysis places Haramiyida within crown Mammalia, suggesting the origin of crown Mammalia in the Late Triassic period and diversification in the Jurassic, which contrasts other estimated divergence times of crown Mammalia. The new haramiyid reveals additional mammalian features of the group, helps to identify other haramiyids represented by isolated teeth, and shows again that, regardless of various phylogenetic scenarios, a complex pattern of evolution involving many convergences and/or reversals existed in Mesozoic mammals.

It begs the question...given the other  Haramiyid which was also found, how good are teeth for classifying mammals?