The attached photo show some tracks from a small mammal from an Early Eocene site in western Washington, USA. The radiometric age is 54 Ma. The setting is a low elevation riverbank in a semitropical environment. The footprints consist of 5-toed tracks with narrow digits terminating in slender sharp claws.The stride/gait indications suggest a narrow-bodied animal with fairly long legs, about the size of a modern possum or racoon. Tracks like this have not previously been reported. I welcoming speculations as to a possible track maker.
Thanks, George
George:
Do have a look at this link for mammalian tracks from Eocene more or less matching with the ones you documented:
https://www.researchgate.net/publication/263308896_Mammal_and_Bird_Tracks_from_the_Eocene_Puget_Group_Northwest_Washington_USA/figures
Best
Syed
Article Mammal and Bird Tracks from the Eocene Puget Group, Northwes...
Syed,
I am not aware of any Eocene tracks that resemble these. Based on comparison to skeletal remains, the size and form of these tracks, the early Eocene age suggests a few possibilities. One is that the track maker was a miacoid. They were abundant and diverse in North America during this time. Many of the members of this group were pretty small, but a likely possibility might by one of the vivveravid "feiliform" miacoids. The trackways appear pretty similar to those of the modern Civet Cat, and the semitropical riverbank paleoenvironment seemsto fit; extant Civet Cats commonly inhabit similar environments. So, that's my first guess, but I'm interested in suggestions from others.
Thanks, George
Syed,
Here are a few more references to Eocene tracks.
Best wishes, George
Dear George
check out: Sarjeant & Langston (1994) Vertebrate Footprints and invertebrate traces form the Chadronian (Late Eocene) of Trans-Pecos Texas. Texas Memorial Museum Bulletin 36.
I think the tracks were made by carnovires (Mustelids or Amphicyonids)
All the best
Christian
Christian,
Thanks for the quick response. I am familiar with the Sarjeant & Langston monograph. The mustelid tracks they describe have much shorter digit lengths, and the digits terminate in curved claws. The amphicyonid tracks (ichnogenus Axiciapes) have very short, broad digits. Sarjeant, Reynolds, and Kissel Jones (2002) described a different amphycyonid Miocene track from California (ichnogenus Herpexipedes). Those tracks have elongate digits, but the size is much larger than the Washington tracks. Also, the interdigital angles are quite narrow, almost parallel. The Washington tracks have much broader interdigital angles.
Best wishes, George
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