Лабокания

Лабокания – один из малоизученных видов плотоядных динозавров. Обитал этот ящер более 70 миллионов лет назад на территории современной Калифорнии в позднем меловом периоде. Назван динозавр в честь скалы Ла Бокана в Северной Америке, где в 1974 году были найдены его останки.

Paleoartist - Brett Booth

Летом 1970 года Национальным Географическим Обществом, была организована коллективная палеонтологическая экспедиция, возглавляемая геологом Уильямом Дж. Моррисом, в Арройо-дель-Росарио в Калифорнии. Во время поисков, волонтер Джеймс Харли Гарбани обнаружил скелет теропода, обитавшего в поздний меловой период.

На данный момент найдены лишь череп и несколько костей скелета этого существа, поэтому трудно даже установить его внешний облик. Судя по найденным останкам, лабокания имела длину около 7 м и весила около 3 тонн. Строение черепа этого динозавра резко отличается от других хищников: он очень узок и вытянут в передней части, из-за чего напоминает голову современных ящериц и змей.

Огромные острые зубы лабокании выдают в динозавре хищника, но, по мнению специалистов, он был тяжёлым и неповоротливым, благодаря чему мог подвергаться нападениям своих более ловких сородичей. Вероятно, в качестве дополнительной защиты лабокании служила её толстая кожа.

Quilmesaurus

Quilmesaurus is a genus of carnivorous theropod dinosaur from the Patagonian Upper Cretaceous (Campanian stage) of Argentina.

Paleoartist - anto009

Discovery and naming

During the late 1980s, a field crew from the Universidad Nacional Tucumán, led by Jaime Powell, uncovered forty kilometres south of Roca City, in Río Negro province, northern Argentina, the remains of a theropod near the Salitral Ojo de Agua. In 2001, Rodolfo Aníbal Coria named and described the type species Quilmesaurus curriei. The genus name is derived from the Quilme, a Native American people, and the specific name honours Dr. Philip John Currie, a Canadian theropod specialist.

The holotype and currently only specimen was designated the collection number MPCA-PV-100, in the Museo Provincial "Carlos Ameghino". It consists of the distal lower half of the right femur (thighbone), and a complete right tibia (shinbone), collected from the Allen Formation of the Malarge Group in the Neuquén Basin. These deposits date from the Campanian to Maastrichtian. The specimen came from the fluvial sandstones at the bottom of the Allen Formation. The taxon is notable as it represents one of the youngest records of a non-avian theropod from Patagonia.

Description

Quilmesaurus is estimated to have measured five to six meters (sixteen to twenty feet) in length. It was originally found be distinguished by unique features of the leg: a well developed mesiodistal crest on the femur; a hooked cnemial crest on the tibia; a asymmetrical distal tibia end; and possessing a later maleolus two times larger than the medial maleolus.

Classification

When originally described, Coria could not find a more precise placement for Quilmesaurus than Theropoda. The presence of a notch in the distal articular surface of the tibia was cited by him as evidence of a possible relationship with basal Tetanurae, which would be surprising as Quilmesaurus lived during a time when South American theropod assemblages were dominated by abelisaurids and carcharodontosaurs. Other theropod material has been recovered from within these same strata and has in 2005 also provisionally been referred to the Tetanurae. However, in 2004 Rubén Juárez Valieri e.a. concluded that Quilmesaurus, in view of the hatchet-shaped cnemial crest, was a member of the Abelisauridae. In 2007 a subsequent study found that Quilmesaurus more precisely belonged to the Carnotaurinae, as shown by the pending lobe of that crest. Juárez Valieri was unable to establish a single autapomorphy of the taxon, concluding that Quilmesauruswere a nomen vanum.

Paleoecology

Other dinosaur remains recovered from the Allen Formation include titanosaurs (Aeolosaurus), a lambeosaurine hadrosaur, a nodosaurid, and dinosaur eggs.

Epanterias

Epanterias is a dubious genus of theropod dinosaur from the Kimmeridgian-Tithonian-age Upper Jurassic upper Morrison Formation of Garden Park, Colorado. It was described by Edward Drinker Cope in 1878. The type species is Epanterias amplexus.

Paleoartist - Uenom

This genus is based on what is now AMNH 5767, parts of three vertebrae, a coracoid, and a metatarsal. Although Cope thought it was a sauropod, it was later shown to be a theropod. Gregory S. Paul reassessed the material as pertaining to a large species of Allosaurus in 1988 (which he classified asAllosaurus amplexus). Other authors have gone further and considered E. amplexus as simply a large individual of Allosaurus fragilis. In 2010, Gregory S. Paul and Kenneth Carpenter noted that the E. amplexus specimen comes from higher in the Morrison Formation than the type specimen of Allosaurus fragilis, and is therefore "probably a different taxon". They also considered its holotype specimen not diagnostic and classified it as a nomen dubium.

Xenotarsosaurus

Xenotarsosaurus is a genus of abelisaurid theropod dinosaur that lived during the Late Cretaceous of Argentina. In 1980 geologist Juan Carlos Sciutto discovered a rich fossil site six kilometres north of the Ocho Hermanos ranch in Chubut province. Among the fossils found there were some theropod remains. Later, a team led by Argentinian paleontologist José Fernando Bonaparte recovered some more theropod bones, possibly from the same individual.

Artist -Sergey Krasovskiy

In 1986, Ricardo Martínez, Olga Giménez, Jorge Rodríguez and Graciela Bochatey described the theropod fossils and coined the genus and species Xenotarsosaurus bonapartei for them. The generic name is derived from Greek xenos, "strange",tarsos, "tarsus", and sauros, "lizard", a reference to the exceptional build of the ankle. The specific name bonapartei honours Bonaparte.

The type specimens (and only known fossils of Xenotarsosaurus) were found in the Bajo Barreal Formation. In 1986 this formation was seen as Campanian; today it is thought to date to the earlier Cenomanian–Turonian. The bones consist of two cotypes: UNPSJB PV 184, a series of two anterior dorsal vertebrae, and PVL 612, a right hind limb including the 611 millimetres (24.1 in) long femur, the tibia, fibula and astragalocalcaneum of the ankle. The exceptional complete fusion, without sutures, of the astragalus and calcaneum, forming an element that is again fused to the widened lower end of the tibia, occasioned the generic name.

The remains show some similarities to Carnotaurus sastrei, causing the describers to assign Xenotarsosaurus to the Abelisauridae, which has remained a common determination. However, it has also been proposed that Xenotarsosaurus is a neoceratosaurian of uncertain affinities.