A nearly complete skull discovered in Arizona has provided paleontologists with unparalleled insights into Adelphyllus cansensis, a mysterious feline species that roamed North America over 5 million years ago and represents an early branch of the saber-toothed cat lineage.
Life of Adelphyllus cansensis based on recently analyzed materials. Image credit: Jesus Gamarra.
Experts refer to Adelphyllus cansensis as an early branching cat from the order Machairodontia, which existed in North America between 7 and 5 million years ago.
This fascinating species was first identified in 1934 from a jaw fragment unearthed in Kansas.
While other fossils were suspected to belong to Adelphyllus cansensis, the anatomy remained poorly understood until the analysis of a nearly complete skull.
“Felids from the Machairodontia order like Adelphyllus cansensis were the size of modern pumas,” noted paleontologists Narimane Chater and Z. Jack Tseng from the University of California, Berkeley. “The holotype consists of nearly complete left and right maxilla bones with dental remains.”
“Subsequent discoveries have added to our understanding of this species,” they added.
In 1983, some postcranial remains found in Mojave County, Arizona, were linked to this species, but a complete set of fossils—including a nearly intact skull with associated canine teeth and jaw fragments—had not been described until now.
In their latest study, Chater and Tseng evaluated this material preserved at the American Museum of Natural History.
The specimen revealed a cat comparable in size to a cougar, revealing early traits of saber-toothed creatures.
The upper canines were flat and serrated, though less pronounced than those seen in iconic saber-toothed species like Smilodon.
“The upper canines of early saber-toothed ancestors were shorter. The findings support our hypothesis that once these hypercarnivores began developing elongated fangs, they couldn’t revert to a less specialized form,” the researchers remarked.
The team’s analysis indicated that the narrow snout of this species resembled that of Metaurus, the oldest saber-toothed cat known from Eurasia, while its rounded skull closely paralleled another primitive genus, Yoshi.
However, Adelphyllus cansensis exhibited notably thin cheekbones and distinct dental characteristics.
“We have never encountered a lineage displaying a regression in the development of long upper canine teeth. Evolution in saber-toothed carnivores tends to move toward more specialized forms,” Dr. Chater explained.
The study also addressed ongoing taxonomic debates, finding that some fossils previously categorized as Shudaellus, a diverse group of primitive felids, should be reassigned to Adelphyllus cansensis.
Describing Shudaellus as a “trash can genus” for mid-sized Miocene felines, the researchers emphasized the relevance of their findings in understanding the early evolution of saber-toothed cats.
During the late Miocene epoch, carnivores migrated between Eurasia and North America via the Bering Land Bridge.
The discovery of Adelphyllus cansensis suggests separate migratory events for early saber-toothed cats into North America, differing from the migration of primitive cats.
“While we are still piecing together the timeline of dispersal events in North America’s fossil record, our findings suggest that the skull material of Adelphyllus cansensis represents an intermediate morphotype between Yoshi and Metaurus, situated at the base of macrodontian diversification,” they concluded.
The team’s research paper was published in the Journal of Vertebrate Paleontology.
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Narimane Chattar & Z. Jack Tseng. New material of Adelphyllus cansensis shedding light on the cranial anatomy of early-diverging felines from the order Machairodontales. Journal of Vertebrate Paleontology published online June 19, 2026. doi: 10.1080/02724634.2026.2667939
Source: www.sci.news