Evaluating morphological characters used to distinguish dire wolves from other canids

Abstract

The evolutionary origin of the dire wolf (Aenocyon dirus), a large wolf-like canid that occurred across North America and into South America during the late Pleistocene, is not fully understood. While originally described as Canis dirus, the classification within the Canis genus has not always been supported, with the alternative Aenocyon genus proposed and subsequently synonymized. Morphological phylogenies supported this taxonomic interpretation, but it was recently resurrected by a genetic study that indicated the dire wolf is a divergent lineage and offered an alternative phylogenetic hypothesis. Previous phylogenetic descriptions based on morphology suggested dire wolves being of the same stock as the extinct Canis armbrusteri and represented as a sister group to the extant gray wolf (Canis lupus). Distinguishing dire wolf characters include broad palate and frontal regions and a high sagittal crest with a backwards extension that exceeds other wolves. Aenocyon dirus is generally considered to be more robust than other wolves, but shares dental synapomorphies with C. armbrusteri, as well as sharing dental and cranial synapomorphies with C. lupus. Dental autapomorphies associated with hypercarnivory appear to differentiate dire wolves from other canids. However, if the alternative genetic based phylogeny is correct in identifying A. dirus as a divergent line from Canis, it is possible that similar morphological features are influenced by convergence, thereby also influencing morphology-based phylogenies. With this in mind, this project reviews past criteria for separating dire wolves and explores the use of micro-CT technology on canid crania, particularly of the basicranium and inner ear, as a novel source for identifying characters to further investigate the phylogenetic relationships of these canids based on morphology. An assessment of basicranial foramina, as well as measurements of the bony labyrinth, will be used to explore alternative features as possible phylogenetic signals when discussing dire wolf phylogeny.

Start Time

16-4-2025 9:00 AM

End Time

16-4-2025 11:30 AM

Presentation Type

Poster

Presentation Category

Science, Technology and Engineering

Student Type

Graduate Student - Masters

Faculty Mentor

Blaine Schubert

Faculty Department

Geosciences

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Apr 16th, 9:00 AM Apr 16th, 11:30 AM

Evaluating morphological characters used to distinguish dire wolves from other canids

The evolutionary origin of the dire wolf (Aenocyon dirus), a large wolf-like canid that occurred across North America and into South America during the late Pleistocene, is not fully understood. While originally described as Canis dirus, the classification within the Canis genus has not always been supported, with the alternative Aenocyon genus proposed and subsequently synonymized. Morphological phylogenies supported this taxonomic interpretation, but it was recently resurrected by a genetic study that indicated the dire wolf is a divergent lineage and offered an alternative phylogenetic hypothesis. Previous phylogenetic descriptions based on morphology suggested dire wolves being of the same stock as the extinct Canis armbrusteri and represented as a sister group to the extant gray wolf (Canis lupus). Distinguishing dire wolf characters include broad palate and frontal regions and a high sagittal crest with a backwards extension that exceeds other wolves. Aenocyon dirus is generally considered to be more robust than other wolves, but shares dental synapomorphies with C. armbrusteri, as well as sharing dental and cranial synapomorphies with C. lupus. Dental autapomorphies associated with hypercarnivory appear to differentiate dire wolves from other canids. However, if the alternative genetic based phylogeny is correct in identifying A. dirus as a divergent line from Canis, it is possible that similar morphological features are influenced by convergence, thereby also influencing morphology-based phylogenies. With this in mind, this project reviews past criteria for separating dire wolves and explores the use of micro-CT technology on canid crania, particularly of the basicranium and inner ear, as a novel source for identifying characters to further investigate the phylogenetic relationships of these canids based on morphology. An assessment of basicranial foramina, as well as measurements of the bony labyrinth, will be used to explore alternative features as possible phylogenetic signals when discussing dire wolf phylogeny.