Cliff collapse reveals 313-million-year-old fossil footprints in Grand
Canyon National Park

Date:
August 21, 2020
Source:
National Park Service
Summary:
Paleontological research has confirmed a series of recently
discovered fossils tracks are the oldest recorded tracks of their
kind to date within Grand Canyon National Park. In 2016, a geology
professor was hiking with his students when he made a surprising
discovery. Lying next to the trail, in plain view of the many
hikers, was a boulder containing conspicuous fossil footprints.



FULL STORY ========================================================================== Paleontological research has confirmed a series of recently discovered
fossils tracks are the oldest recorded tracks of their kind to date
within Grand Canyon National Park. In 2016, Norwegian geology professor,
Allan Krill, was hiking with his students when he made a surprising
discovery. Lying next to the trail, in plain view of the many hikers, was
a boulder containing conspicuous fossil footprints. Krill was intrigued,
and he sent a photo to his colleague, Stephen Rowland, a paleontologist
at the University of Nevada Las Vegas.


==========================================================================
The trailside tracks have turned out to be even more significant than
Krill first imagined. "These are by far the oldest vertebrate tracks
in Grand Canyon, which is known for its abundant fossil tracks" says
Rowland. "More significantly," he added, "they are among the oldest
tracks on Earth of shelled-egg-laying animals, such as reptiles, and
the earliest evidence of vertebrate animals walking in sand dunes."
The track-bearing boulder fell from a nearby cliff-exposure of the
Manakacha Formation. The presence of a detailed geologic map of the
strata along the Bright Angel Trail, together with previous studies of
the age of the Manakacha Formation, allowed the researchers to pin down
the age of the tracks quite precisely to 313 +/- 0. 5 million years.

The newly discovered tracks record the passage of two separate animals
on the slope of a sand dune. Of interest to the research team is the
distinct arrangement of footprints. The researchers' reconstruction
of this animal's footfall sequence reveals a distinctive gait called
a lateral-sequence walk, in which the legs on one side of the animal
move in succession, the rear leg followed by the foreleg, alternating
with the movement of the two legs on the opposite side. "Living species
of tetrapods―dogs and cats, for example―routinely use a lateral-sequence gait when they walk slowly," says Rowland. "The Bright
Angel Trail tracks document the use of this gait very early in the
history of vertebrate animals. We previously had no information about
that." Also revealed by the trackways is the earliest-known utilization
of sand dunes by vertebrate animals.


========================================================================== Story Source: Materials provided by National_Park_Service. Note: Content
may be edited for style and length.


========================================================================== Related Multimedia:
* Image_of_the_Manakacha_Trackway ========================================================================== Journal Reference:
1. Stephen M. Rowland, Mario V. Caputo, Zachary A. Jensen. Early
adaptation
to eolian sand dunes by basal amniotes is documented in two
Pennsylvanian Grand Canyon trackways. PLOS ONE, 2020; 15 (8):
e0237636 DOI: 10.1371/ journal.pone.0237636 ==========================================================================

Link to news story: https://www.sciencedaily.com/releases/2020/08/200821120756.htm

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