The first megatheropod tracks from the Lower Jurassic upper Elliot Formation, Karoo Basin, Lesotho

Abstract

A palaeosurface with one megatheropod trackway and several theropod tracks and trackways from the Lower Jurassic upper Elliot Formation (Stormberg Group, Karoo Supergroup) in western Lesotho is described. The majority of the theropod tracks are referable to either Eubrontes or Kayentapus based on their morphological characteristics. The larger megatheropod tracks are 57 cm long and have no Southern Hemisphere equivalent. Morphologically, they are more similar to the Early Jurassic Kayentapus, as well as the much younger Upper Cretaceous ichnogenus Irenesauripus, than to other contemporaneous ichnogenera in southern Africa. Herein they have been placed within the ichnogenus Kayentapus and described as a new ichnospecies (Kayentapus ambrokholohali). The tracks are preserved on ripple marked, very fine-grained sandstone of the Lower Jurassic upper Elliot Formation, and thus were made after the end-Triassic mass extinction event (ETE). This new megatheropod trackway site marks the first occurrence of very large carnivorous dinosaurs (estimated body length >8–9 meters) in the Early Jurassic of southern Gondwana, an evolutionary strategy that was repeatedly pursued and amplified in the following ~135 million years, until the next major biotic crisis at the end-Cretaceous.

The oldest ceratosaurian (Dinosauria: Theropoda), from the Lower Jurassic of Italy, sheds light on the evolution of the three-fingered hand of birds

“…We estimate Saltriovenator length at ∼7.5 m, thus resulting the largest Early Jurassic theropod based on skeletal remains (Smith et al, 2007; Carrano & Sampson, 2008). With a body size comparable to many Middle and Late Jurassic tetanurans (Carrano, Benson & Sampson, 2012), Saltriovenator pre-dates the occurrence of large theropods (body mass approaching 1,000 kg) by over 25 My (Benson, 2010; Carrano, Benson & Sampson, 2012), reinforcing a scenario recently suggested on the basis of ichnological evidence (Sciscio et al, 2017). The radiation of larger and relatively stockier averostran theropods earlier than previously known may represent one of the factors that ignited the trend toward gigantism in Early Jurassic sauropods (Sander et al, 2011; McPhee et al, 2018).…”

Late Permian-Early Jurassic vertebrate tracks from patagonia: Biochronological inferences and relationships with southern african realms

“…This is consistent with the absolute dating, seeing that track-bearing surfaces are comprised in a time span between 188-178 Ma (Díaz-Martínez et al, 2017). On the correlation with the Karoo occurrences, some records of the ichnotaxon Moyenisauropus (sensu Ellenberger, 1970) in the upper Elliot (Hettangian-early Sinemurian sensu Sciscio et al, 2017b) have been compared with Anomoepus (Olsen and Rainforth, 2003). Moreover, the age of southern African records allows the correlation with the Marifil Volcanic Complex (Díaz-Martínez et al, 2017).…”

Tracking the Pliensbachian–Toarcian Karoo firewalkers: Trackways of quadruped and biped dinosaurs and mammaliaforms

“…Standard ichnological measurements of the tracks (Fig 2) were taken after Thulborn [59], Romano et al [71], Castanera et al [72] and Sciscio et al [73]. The following parameters were measured, where applicable: pes length (FL), pes width (FW), anterior triangle length (ATL), anterior triangle width (ATW), manus length (ML), manus width (MW), pes pace (PP), pes stride (PS), manus pace (MP), manus stride (MS), pes to manus distance in each step (P-M distance), pes pace angulation (P ANG), manus pace angulation (M ANG), length of respective digits (LII, LIII, LIV), pes track rotation (TRp), manus track rotation (TRm), digit divarication (II^IV, II^III, III^IV), pes trackway width (PTW), manus trackway width (MTW) and pes trackway ratio (PTR).…”