Agustinia

Live reconstruction of Agustinia ligabuei

• Neuquén, Argentina ( Lohan Cura Formation)

• Agustinia ligabuei

Agustinia is a genus of sauropod dinosaur that lived in the Lower Cretaceous of South America. Only species described is Agustinia ligabuei.

The fossil remains of Agustinia only consist of series of the spinous processes of dorsal, sacral and caudal vertebrae, parts of the hind legs and at least three different types of dermal bones (presumably osteoderms ). This dermal bones are preserved in the form of plates and spines and could have been placed along the back line. A recent study has noted, however, that it may have been in these bones not osteoderms, but simple, age-related ossification. The fossils are from the Lohan Cura - Formation ( Upper Aptian to Lower Albian ) in Patagonia (Argentina) and 1999 were described by José Bonaparte scientifically.

Features

The remains of 18 vertebrae were discovered in two rock blocks, the first block of the three posterior dorsal vertebrae, six sacral vertebrae, and two front caudal vertebrae with includes, while the second block of eight of the anterior and middle caudal vertebrae is. The vertebrae are badly weathered, so only spinous processes are preserved. The position of the vortex remnants in a series points out, however, that the vertebrae are little slips after the death of the animal, and represent a series of sequential, articulated vertebrae.

There are eight well-preserved bone osteodermartige known, six of which have remained seemingly get in live position on the vertebrate series. José Bonaparte writes that this interpreted by him as osteoderms bones were arranged following the back and sacral vertebrae in two parallel rows. He suggests further that the osteoderms may have been mechanically connected with each other and with the spinous processes of the vertebrae through tissue. There were at least three unique, existing in this form in any other dinosaur types of dermal bones present: Firstly, there was a leaf-shaped, 21 inches in diameter large plate. A second type is represented by a thin plate with 64 centimeters in diameter, showing two lateral extensions, which may represent the bases of previous long quills. Another four osteoderms each show a lateral extension; presumably, these are about one-half of the second type. A third type is characterized spike- like, forked at one end of the bone by up to 80 centimeters long. These three Osteoderm types can be used to distinguish this species from other genera, according to Bonaparte.

Bonaparte continued to provide six sacral vertebrae fixed, a feature which only show the Titanosauria among sauropods. Tibia and fibula are 84 inches long. The lower half of the tibia was seen from the front ( anteroposterior ) thin, indicating that the shin was thinner than that of titanosaurs as Antarctosaurus or Saltasaurus. The foot bones are the same as Titanosaurier.

System

The scant remains make it difficult to classify Agustinia taxonomically. It matches were found with the Diplodocoidea and Titanosauria, the putative osteoderms and the six sacral vertebrae speak for one belonging to the Titanosauria. So consider Upchurch and colleagues ( 2004) Agustinia as not assignable Titanosauria ( incertae sedis Titanosauria ). Kristina Curry Rogers assigns Agustinia within the Titanosauria in the group Lithostrotia one which includes more modern forms.

Researchers led by Michael D' emic (2009 ) noted, however, that the found remains of the sacral vertebrae are not clearly connected to each other, but that the rearmost and foremost vertebra from the rest of the vertebral series is separated. Thus, it is not clear whether Agustinia actually like the Titanosauria had six sacral vertebrae. Furthermore, the alleged osteoderms of osteoderms other archosaurs differ. So Michael D' emic and colleagues note that one can not exclude that these bones were no osteoderms, but age-related ossification, as they were also detected in the sacral region of Camarasaurus. The researchers conclude that there is no unique features exist that would allow a classification within the Diplodocoidea or Titanosauria and classify Agustinia therefore as not assignable Neosauropoden ( incertae sedis Neosauropoda ).

Bonaparte ordered Agustinia in his first description of an own family, the Agustiniidae. This family should be - just like Agustinia itself - let by the presence of three types distinguished from osteoderms. This family, however, has not found wide acceptance among researchers.

Fund and naming

The Fund was previously only in 1997 by an expedition of the Museo Argentino de Ciencias Naturales ( Buenos Aires ) was discovered a few kilometers west of the city Picún Leufú in the southern province of Neuquen. The rocks of the discovery site belong stratigraphically to the upper portion of the Lohan Cura Formation. This excursion was part of a program of the Museum in 1996 and 1997, had the discovery of new vertebrate fossils in the Lohan Cura Formation goal. So, a year earlier (1996 ), a new sauropod was discovered 50 km west of Picún Leufú.

The name honors the Agustinia former students Agustin Martinelli, who discovered the skeleton and belonged to the excavation team of the Museo Argentino de Ciencias Naturales. The Artepitheth ligabuei honors Giancarlo Ligabue, an Italian supporter of the 1997 expedition to the Lohan Cura Formation.

The Fund ( holotype, specimen number MCF- PVPH -110 ) is now in the Cármen Funes Museum in Plaza Huincul. It consists of the vertebral arches and spines of three back -, six sacral, and caudal vertebrae ten. In addition, the almost complete right shinbone ( tibia) and fibula ( fibula ), five articulated left metatarsals and nine dermal bones has been discovered.

Documents

Main source

• JF Bonaparte: An armored sauropod from the Aptian of northern Patagonia, Argentina. In: Y. Tomida, TH Rich, P. Vickers - Rich ( eds.): Proceedings of the Second Gondwanan Dinosaur Symposium, National Science Museum Monographs. 15, 1999, pp. 1-12 (PDF).