Wednesday, October 8, 2014

[Paleontology • 2014] Tachiraptor admirabilis • New Dinosaur (Theropoda, stem-Averostra) from the earliest Jurassic of the La Quinta Formation, Venezuelan Ande

Tachiraptor admirabilis, unearthed in Venezuela, attacking the herbivorous dinosaur Laquintasaura.
PaleoArt: Maurílio Oliveira | DOI: 10.1098/rsos.140184

Dinosaur skeletal remains are almost unknown from northern South America. One of the few exceptions comes from a small outcrop in the northernmost extension of the Andes, along the
western border of Venezuela, where strata of the La Quinta Formation have yielded the ornithischian Laquintasaura venezuelae and other dinosaur remains. Here, we report isolated bones (ischium and tibia) of a small new theropod, Tachiraptor admirabilis gen. et sp. nov., which differs from all previously known members of the group by an unique suite of features of its tibial articulations. Comparative/phylogenetic studies place the new form as the sister taxon to Averostra, a theropod group that is known primarily from the Middle Jurassic onwards. A new U–Pb zircon date (isotope dilution thermal-ionization mass spectrometry; ID-TIMS method) from the bone bed matrix suggests an earliest Jurassic maximum age for the La Quinta Formation. A dispersal–vicariance analysis suggests that such a stratigraphic gap is more likely to be filled by new records from north and central Pangaea than from southern areas. Indeed, our data show that the sampled summer-wet equatorial belt, which yielded the new taxon, played a pivotal role in theropod evolution across the Triassic–Jurassic boundary 

Tachiraptor admirabilis attacking the herbivorous dinosaur Laquintasaura.
Tachiraptor, a 1.5-meter-long theropod dinosaur (center) that lived in what is now Venezuela just over 200 million years ago,
PaleoArt: Maurílio Oliveira

Theropoda Marsh 1881 sensu 
Neotheropoda Bakker 1986 sensu 

stem-Averostra Paul 2002 sensu  

Tachiraptor admirabilis new genus and species

Etymology: The generic name derives from Táchira, the Venezuelan state where the fossil was found, and raptor (Latin for thief), in reference to the probable predatory habits of the animal. The specific epithet honours Simon Bolivar’s ‘Admirable Campaign’, in which La Grita, the town where the type locality is located, played a strategic role.

Figure 4. Strict consensus of the 1107 MPTs recovered with the inclusion of Tachiraptor admirabilis into the dataset of Xu et al. [12]. Branch colours represent extension of ghost lineages in millions of years (red, less than 15; purple, 15–35; blue, more than 35). Taxon bar lengths correspond to their chronologic distribution/uncertainty (based on various sources). Bar colours match those of the index Middle Jurassic palaeomap [70] and correspond to the provenance of Triassic/Jurassic theropods from the defined palaeobiogeographic provinces (SG, South Gondwana; EA, Euramerica; TU, Transurals; EB, Equatorial Belt) at the time of their occurrences.

Langer, M. C., Rincón, A. D., Ramezani, J., Solórzano, A., and O. W. M. Rauhut. 2014. New Dinosaur (Theropoda, stem-Averostra) from the earliest Jurassic of the La Quinta Formation,
Venezuelan Andes. Royal Society Open Science. 1: 140184. DOI: 10.1098/rsos.140184

New meat-eating dinosaur lived in the wake of a mass extinction @newsfromscience
Newfound South American Predator Snacked on Little Dinosaurs via @LiveScience