Fast spread followed by anagenetic evolution in Eurasian and North American Amphimachairodus

ABSTRACT

The charismatic sabretooth cat Amphimachairodus has numerous but largely fragmentary records across late Miocene deposits of Africa, Eurasia and North America. The genus has a complex taxonomic history, and the majority of Amphimachairodus materials come from isolated localities, often studied without stratigraphic context. Here, we analyse the long, continuous records from the classic Chinese Baode strata, which produce Amphimachairodus throughout the section, and demonstrate that an A. palanderi-horribilis chronospecies succession represents a continuum of in situ anagenetic evolution of increasing size. We then synthesise chronological occurrences of Amphimachairodus from all Holarctic records and reframe their evolution as a case of chronospecies succession. Two parallel anagenetic lineages are evident: a Eurasian A. giganteus-palanderi-horribilis chronospecies succession and second, a North American A. coloradensis-alvarezi chronospecies succession following an immigration event in the early Hemphillian. In addition to greater hypercarnivory evidenced by dental specialisation, the Eurasian lineage shows a trend towards a large body size, whereas the North American lineage decreases in size. We take this opportunity to describe materials of Amphimachairodus alvarezi from Yepómera (latest Hemphillian) in the state of Chihuahua, Mexico, and previously undescribed materials from San Miguel de Allende Basin. We review taxonomic status of Chinese A. horribilis and related taxa.

KEYWORDS:

• Sabretooth
• Amphimachairodus
• late Miocene
• Holarctic
• anagenetic evolution
• chronospecies

Acknowledgments

We thank Gertrud Rössner for permission to publish on specimens from Staatliche Naturwissenschaftliche Sammlungen Bayerns - Bayerische Staatssammlung für Paläontologie und Geologie under her care. Yanping Song helped with Photoshop processing of images. We thank Sam McLeod for providing LACM locality images. We thank Zhang Zhaoqun and Mikael Fortelius for discussion on Baode localities and biostratigraphy. Jesus Silva Corona of Centro de Geociencias took photographs of select specimens. We thank two anonymous reviewers for their detailed comments and suggestions that have greatly improved our paper. We are grateful for financial and logistic assistance from Centro de Geociencias and Museo de Paleontoogía Geociencias Juriquilla, Universidad Nacional Autónoma de México.

Disclosure statement

No potential conflict of interest was reported by the author(s).

Correction Statement

This article has been corrected with minor changes. These changes do not impact the academic content of the article.

Additional information

Funding

This research was supported by a grant from the National Science Foundation [EAR-1949742].