A new paper (and another reason to be concerned by reduction of Bears Ears National Monument. Valley of the Gods was removed...)
Adam K. Huttenlocker, Amy Henrici, W. John Nelson, Scott Elrick, David S. Berman, Tyler Schlotterbeck & Stuart S. Sumida (2018)
A multitaxic bonebed near the Carboniferous-Permian boundary (Halgaito Formation, Cutler Group) in Valley of the Gods, Utah, USA: vertebrate paleontology and taphonomy.
Palaeogeography, Palaeoclimatology, Palaeoecology (advance online publication)
Highlights
We describe the oldest continental vertebrate assemblage in the Cutler Group (Carboniferous-Permian) of Bears Ears National Monument, Paradox Basin, SE Utah
The assemblage is preserved as a multitaxic bonebed formed in a seasonally wet, low relief flood plain environment that periodically hosted a diverse riparian flora and fauna, prior to the Permian desertification of the Paradox Basin region
Vertebrate taxa include terrestrial tetrapods that correspond to the lower or middle El Cobrean Canyon Formation assemblages in New Mexico (Cobrean and Coyotean land vertebrate faunachrons), supporting their late Pennsylvanian age
The assemblage reinforces that dryland-adapted tetrapods proliferated early in northwestern Pangea, foreshadowing the iconic Permian redbeds faunas of north-central Texas
Abstract
The Carboniferous-Permian (C-P) transition records a shift in the composition and environmental setting of tropical flora and vertebrate assemblages across western and central Pangea. Here we report the discovery of a rare, multitaxic bonebed in the lower Halgaito Formation (Cutler Group) in Valley of the Gods and its vicinity (San Juan County), southeast Utah, USA. The assemblage, which comprises carcasses and disarticulated bones and teeth, preserves aquatic and semi-terrestrial elements including xenacanth chondrichthyans, actinopterygians, sagenodontid lungfish, and the temnospondyl amphibian Eryops, together with terrestrial taxa including the synapsids, Ophiacodon navajovicus, Edaphosaurus, and Sphenacodon, and a hitherto undescribed araeoscelidan reptile. Sedimentological, paleontological, and strontium isotopic evidence indicates the bonebed formed as a slackwater deposit at the confluence of a major freshwater stream channel and its tributary. The deposit probably formed through late stage flooding of a likely bottlenecked fluvial system, consistent with increasingly episodic or seasonal precipitation, concentrating carcasses of immature and mature shore-dwelling animals. Comparisons with vertebrate assemblages in the Cutler Group of New Mexico, USA suggest that the assemblage is correlative with the lower or middle assemblage of the El Cobre Canyon Formation (Cobrean and Coyotean Land Vertebrate Faunachrons; LVFs), and as such, is of latest Carboniferous age. Our findings strengthen the hypothesis that dryland-adapted vertebrate communities proliferated earlier in westernmost Pangea, well before earliest Permian time, compared to other tropical regions.
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