Fossil tracks push range of large bird northward
Rod Boyce
907-474-7185
Nov. 4, 2024
Scientists from Fairbanks, New Mexico and Japan have discovered the first reported fossilized tracks of a large four-toed bird that inhabited central Alaska 90 million to 120 million years ago.
A description of the two tracks was published in August in a special edition of the and presented Wednesday at the annual meeting of the Society of Vertebrate Paleontology in Minneapolis.
A photograph made during fieldwork along the Yukon River in central Alaska in 2023 shows the four-toed track.
The bird tracks were found in 2023 in mid-Cretaceous rock near the communities of Nulato and Kaltag. The location significantly extends northward the known geographic range of this type of track.
The work was led by paleontologist Anthony Fiorillo, executive director of the New Mexico Museum of Natural History and Science.
The August papers co-authors include 51窪蹋勛圖厙 geology professor Paul McCarthy with the 51窪蹋勛圖厙 College of Natural Science and Mathematics and 51窪蹋勛圖厙 Geophysical Institute, and associate professor of paleontology Yoshitsugu Kobayashi of Hokkaido University.
Rather than a geographic oddity, we submit that the tracks described here offer further insight into the importance of the ancient Arctic in terms of bird biodiversity, the authors write.
The newly discovered fossil tracks, found among several fossil tracks of smaller birds, are of a large four-toed bird and show three toes pointing forward and one pointing toward the rear. The toes are unwebbed.
We found a fair number of fossil bird footprints, Fiorillo said. We found smaller bird footprints that would belong to something comparable to a modern-day shorebird such as a willet or an avocet.
Then we found the footprints that are much larger, he said. They were more crane size or slightly bigger, more like whooping crane size.
Fiorillo places the tracks in the Archaeornithipus ichnogenus, a classification of the most primitive birds. Archaeornithipus was first coined in 1996 to describe fossil tracks found in Soria, Spain.
A heat map shows the general morphology of the four-toed fossil track.
An ichnogenus is a classification used to group trace fossils such as footprints, burrows or feeding marks that share similar characteristics. Trace fossils represent the behavior of organisms but do not necessarily indicate the species that made them.<