Hyloidichnus bifurcatusGilmore, 1927 andLimnopus heterodactylus(King, 1845) from the Early Permian of Southern Alps (N Italy): A New Equilibrium in the Ichnofauna

Abstract

Studies on Early Permian tetrapod ichnofauna emphasized the scarcity of forms from Italian sites. A revision work on the entire collections revealed the presence of Hyloidichnus bifurcatusGilmore, 1927 and Limnopus heterodactylus (King, 1845). The ichnoassociation now lists seven ichnogenera: Amphisauropus, Batrachichnus, Dromopus, Erpetopus, Hyloidichnus, Limnopus, Varanopus. These new data enlarge the ichnoceonosis, adding tracks of medium-size captorhinomorphs (Hyloidichnus) and temnospondyls (Limnopus) to the Italian ichnofauna, previously characterized by scarcity of predators and amphibians. Radiometric ages give a strong age constraint to the ichnoassociation (Early Kungurian), allowing useful correlations to contemporary successions all over the world. The main difference is the absence of Ichniotherium and Dimetropus, and this could have a stratigraphic or paleoenvironmental significance. The fauna is similar in two main basins, Collio and Orobic. It differs solely in the proportions between ichnotaxa, with a predominance of areoscelid traces (Dromopus) in the Collio Basin and of captorhinomorph traces (Erpetopus, Varanopus, Hyloidichnus) in the Orobic Basin. This datum could reflect slightly different environments, seasonal in the Collio Basin (alluvial plain) and more arid in the Orobic Basin (playa-like). The lack of some forms in smaller basins of the Athesian Volcanic Complex is probably due to a bias.

Permian tetrapod footprints from the Spanish Pyrenees

“…6A) and UGKU 1965 correspond well with tracks of Hyloidichnus Gilmore, 1927. Hyloidichnus is similar to Varanopus Moodie, 1929; both ichnotaxa mainly differ in the relative length of the fifth digit of the pes imprint and by the size range of the imprints (Voigt et al, 2009Hminna et al, 2012;Marchetti et al, 2013). Digit V of the pes imprint is about the length of digit I in Hyloidichnus, whereas it is as long as II or III in Varanopus.…”

“…While Batrachichnus, Limnopus and Dromopus occur in both Carboniferous and Permian strata, Varanopus and Hyloidichnus are hitherto known from Permian successions only (Geinitz, 1861;Marsh, 1894;Woodworth, 1900;Pabst, 1908;Baird, 1952;Haubold, 1970Haubold, , 2000Gand, 1988;Haubold et al, 1995;Nicosia et al, 2000;Santi and Krieger, 2001;Gand and Durand, 2006;Voigt et al, 2009Voigt et al, , 2010Voigt et al, , 2011aVoigt et al, , 2012Marchetti et al, 2013;Marchetti, 2014). Varanopus has mainly been reported from Early Permian strata (Haubold, 1971;Gand, 1988;Lucas, 2001, 2003;Lucas et al, 2001;Van Allen et al, 2005;Marchetti, 2014), suggesting that the footprint level of the Peranera Formation at UGKU locality 34 is of the same age.…”

“…This ichnotaxon is well known from many localities with Carboniferous and Permian tetrapod footprints in North America, Europe and Africa (Haubold, 1970(Haubold, , 1996Haubold and Sarjeant, 1973;Gand, 1988;Haubold et al, 1995;Lucas et al, 2005;Voigt et al, 2011aVoigt et al, , 2011bMarchetti et al, 2013). B. salamandroides from the Early Permian of the Czech Republic is the first available ichnospecies of Batrachichnus (Geinitz, 1861;Haubold, 1996).…”

“…Tracks of this ichnogenus are well-known from Early Permian deposits of Germany (Müller, 1954;Haubold, 1998), France (Gand, 1988), the United States Lucas, 2001, 2003;Lucas and Spielmann, 2009), Canada , and Italy (Nicosia et al, 2000;Marchetti et al, 2013;Marchetti, 2014). Varanopus is most similar to tracks assigned to Notalcerta Butts, 1891, Hyloidichnus Gilmore, 1927, Erpetopus Moodie, 1929and Robledopus Voigt et al (2013, but significant differential characters between these ichnotaxa were recently recorded in detail .…”

“…Therefore, we consider V. curvidactylus a junior synonym of V. microdactylus. A number of Varanopus tracks from the Hermit and Arroyo de Alamillo formations of the United States (Gilmore, 1927;Lucas and Spielmann, 2009), the Rabejac Formation of France (Gand, 1988), the Collio and Pizzo del Diavolo formations of Italy (Nicosia et al, 2000;Marchetti et al, 2013;Marchetti, 2014) and the Çakraz Formation of Turkey (Gand et al, 2011), however, differ from V. microdactylus by a relatively shorter fifth digit of the pes imprint. The same observation was independently made for Varanopus from the Pizzo del Diavolo Formation of the Southern Alps and, consequently, application of a separate ichnospecies claimed (Marchetti et al, 2013).…”