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Protochirotherium archosaur tracks from Central Pangea



From: Ben Creisler
bcreisler@gmail.com

A new paper:

Hendrik Klein, Grzegorz Niedźwiedzki, Sebastian Voigt, Abdelouahed
Lagnaoui, Abdelkbir Hminna, Hafid Saber & Jörg W. Schneider (2013)
The Tetrapod Ichnogenus Protochirotherium Fichter and Kunz 2004, a
Characteristic Early Triassic Morphotype of Central Pangea.
Ichnos 20(1):24--30
DOI:10.1080/10420940.2012.757699
http://www.tandfonline.com/doi/full/10.1080/10420940.2012.757699



Early Triassic chirotherian footprint assemblages from Poland,
Germany, and Morocco are important for understanding archosaur
evolution in the aftermath of the Permian-Triassic crisis. However,
their ichnotaxonomy is confusing because various authors have
interpreted their diversity differently. After an analysis and
ichnotaxonomic re-assessment, the presence of the ichnogenera
Brachychirotherium, Isochirotherium, and Chirotherium in these
assemblages is not supported. Distant similarities with these
ichnotaxa are functions of extra morphological variation and
substrate-related factors. Instead, Early Triassic chirotherian
footprints described under these names are assigned here to the
ichnogenus Protochirotherium and to a more slender morphotype
identified as Synaptichnium. In particular, Protochirotherium appears
to be more widely distributed in central Pangea as a characteristic
morphotype reflecting a distinct stage in archosaur evolution.
Trackmakers were nonarchosaurian archosauriforms or, alternatively,
stem-group crocodylians. Morphologically and temporally these
footprints match the hypothetical ancestor of the Chirotherium barthii
trackmaker. Chirotherium barthii appears by the beginning of the
Middle Triassic. Because of its restricted stratigraphic range, and
its wider distribution in central Pangea, Protochirotherium also has
biostratigraphic significance for this region and can be considered as
an indicator of Early Triassic-aged strata.