Late Carboniferous Tetrapod Footprints from the Souss Basin, Western High Atlas Mountains, Morocco

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“…12, 14A-B). Pinpointing these changes among Ichniotherium cottae tracks to diadectid phylogeny is mostly guesswork: If the assignment of the Bromacker Ichniotherium cottae to Diadectes ("Silvadectes") absitus according to Voigt, Berman & Henrici (2007) (Reisz 2007, Kissel 2010see Figs. 2, 18B).…”

“…Following an early phase of evolutionary change in posture and locomotion with a reduction in the degree of sprawling, shortening of the trunk, slight pronation of the hands during ground contact and somewhat higher walking speeds, the later transformation of the trackway pattern towards a more pronounced inward orientation of the manual and pedal imprints indicates a further change in posture which arises in combination with a further increase in walking speed. Diadectid evolution is thought to have been shaped by adaptation to a herbivorous lifestyle which is visible in the phylogenetic transformation of the skull towards higher ability of processing plant material, but also in the gaining of body sizes that are not matched by more basal carnivorous terrestrial tetrapods (Sues & Reisz, 1998;Reisz & Sues, 2000;Kissel, 2010, Reisz & Fröbisch 2014. In conflict with a late or continuous increase in Ichniotherium trackmaker body size, the earliest occurrences from the Late Carboniferous and Carboniferous/Permian boundary include the largest individuals, i.e.…”

“…With some exceptions (e.g., Ruta and Coates, 2007), phylogenetic analyses of basal amniotes and their non-amniote relatives recovered the diadectomorphs as a monophylum that forms the sistergroup to amniotes and consists of Limnoscelis, Tseajaia as well as five or more diadectid taxa that range from the Late Carboniferous through the late Early Permian (e.g., Laurin & Reisz 1999Ruta, Coates & Quicke, 2003;Reisz 2007, Kissel 2010Fig. 2).…”

“…If the assignment of a fragmentary skull from China to diadectids by Liu & Bever (2015) is confirmed, it would extend the range of this group by over 15 million years into the Late Permian. Based on the unique track-trackmaker co-occurrences of the Early Permian Bromacker site in central Germany (Voigt, Berman & Henrici, 2007), Ichniotherium sphaerodactylum with relatively long pedal digit V can be related to Orobates pabsti (Berman et al, 2004), whereas Ichniotherium cottae with relatively short pedal digit V is likely to be the track of Diadectes absitus (Berman, Sumida & Martens, 1998), which has been referred to the new genus Silvadectes by Kissel (2010). A short pedal digit V and phalangeal formula 2-3-4-5-3 has been documented for the North American Diadectes specimen CM 41700 (and was probably also present in Diadectes ("Silvadectes") absitus, see Voigt, Berman & Henrici, 2007) whereas the relatively long pedal digit V and pedal phalangeal formula 2-3-4-5-4 occurs in both, the basal diadectomorph Limnoscelis (e.g., Kennedy, 2010: fig.…”

“…8) and the diadectid Orobates. Thus, we consider a clade of diadectids which share a pes with relatively short digit V and are more closely related to the North American species of Diadectes (sensu Kissel, 2010) than to Orobates as the potential producer group of all documented Ichniotherium tracks with relatively short pedal digit V. This type of Ichniotherium represents a well-defined subset of all Ichniotherium tracks (including Ichniotherium cottae from the Thuringian forest) and spans 20 million years of the geological record. In order to find out whether Ichniotherium with relatively short pedal digit V, a) can be subdivided into ichnotaxonomically relevant morphotypes based on imprint and trackway measurement data and b) includes variability indicative for evolutionary change in trackmaker locomotion, the following steps are undertaken in the present approach:…”