Потребителски вход

Запомни ме | Регистрация
Постинг
15.01.2016 00:44 - Largest prehistoric animals Vol.1 Vertebrates part9 Reptilies ch.1 Еarly reptiles
Автор: valentint Категория: Забавление   
Прочетен: 409 Коментари: 0 Гласове:
0

Последна промяна: 05.12.2016 19:37


Smok wawelski

Smok (meaning "dragon" in Polish) is an extinct genus of large carnivorous archosaur. It lived during the latest Triassic period (latest Norian to early Rhaetian stage, between 205–200 Ma). Its remains have been found in Lisowice, southern Poland. The type species is Smok wawelski (after the Wawel Dragon) and was named in 2011. It is larger than any other known predatory archosaur from the Late Triassic or Early Jurassic of central Europe. The relation of Smok to other archosaurs has not yet been thoroughly studied; it may be a rauisuchid, prestosuchid or ornithosuchid crurotarsan (part of the crocodile line of archosaurs) or a theropod dinosaur (part of the bird line of archosaurs).

At an estimated 5 to 6 metres (16 to 20 ft) in length, Smok was the largest carnivorous archosaur in central Europe at the time. It was larger than any other known theropod dinosaur or pseudosuchian living in central Europe during either the Late Triassic or Early Jurassic. The skull is 50 to 60 centimetres (20 to 24 in) long.

Several features indicate that Smok is an archosaur, including serrated teeth, a contact between the jugal and quadratojugal bones at the back of the skull, a hole in front of the eye socket called the antorbital fenestra, maxillae bones in the upper jaw that connect along their palatal processes, and a rounded projection on the upper part of the femur bone.

The braincase of Smok includes many derived (advanced) features. The most prominent of these is a funnel-shaped structure on the bottom of the braincase, formed by a very wide, rounded basisphenoid bone. A deep notch called the basisphenoid recess cuts into the back of this funnel. Above the funnel is a very thin area of the braincase that is formed by deep depressions on the basisphenoids.

Smok has several features that are shared with both dinosaurs and crocodile-line archosaurs, making classification difficult. Similarities with theropods include a groove, or antitrochanter, on the ilium bone of the hip that is part of the acetabulum (a depression where the head of the femur attaches to the hip). Smok and theropods also have an anterior trochanter on the femur. Some large theropods share with Smok the deep depressions of the basisphenoids in the braincase. Similarities with rauisuchians include a triangular antorbital fenestra and a connection between the ectopterygoid and jugal bones of the skull that is split into two projections. The hip of Smok has a ridge on the lateral surface of the ilium above the acetabulum. This ridge is a defining characteristic of rauisuchians, forming a buttress over the femur and giving these animals a pillar-erect stance.

Other features of Smok seem to exclude it from these groups of archosaurs. The premaxilla and maxilla of the upper jaw attach closely to each other, making a continuous row of evenly spaced teeth. Early theropods and orthithosuchids have a toothless gap between the premaxilla and the maxilla, distinguishing them from Smok. The upper jaw bones of rauisuchians are not closely connected, leaving a small opening between the premaxilla and maxilla that is not seen in Smok. Unlike many pseudosuchids and theropods, Smok does not have pneumatic areas, or air pockets, in the braincase. It also has several features that link it with primitive archosauromorphs, including the presence of a postfrontal bone on the skull and a closed acetabulum in the hip.

Smok was the largest predator in its environment. Other large predatory archosaurs included the dinosaur Liliensternus and the rauisuchids Polonosuchus and Teratosaurus, but these animals were much smaller than Smok. It was one of the largest archosaurs in the world during the Late Triassic, and larger archosaurs did not appear until after the Early Jurassic. Smok lived alongside small carnivorous dinosauromorph and poposauroid archosaurs and large herbivorous dicynodonts.


Erythrosuchus

Erythrosuchus (red crocodile) is an extinct genus of archosauriform reptile from the Triassic of South Africa and Namibia. Remains have been found from the Cynognathus Assemblage Zone of the Beaufort Group in the Karoo of South Africa as well as the Omingonde Formation in Namibia.

In the Late Triassic, the ecological niche left by Erythrosuchus was filled by creatures like Saurosuchus and Postosuchus.

Erythrosuchus was the largest predator of its time, at around 5 metres (16 ft) long and 2.1 metres (6.9 ft) tall[citation needed]. It walked on all fours and had limbs which were positioned semi-vertically under its body, unlike the more sprawling gait of most earlier reptiles. Its head was large and dinosaur-like, reaching a length of 1 metre (3.3 ft), and had sharp, conical teeth.

Erythrosuchus was the largest erythrosuchid, but apart from its size, it was similar in appearance to other related genera. It had a large head and comparatively short neck. One of the few distinguishing features of Erythrosuchus other than its size is the smoothness of the margin of the squamosal, a bone at the rear of the skull. In other erythrosuchids, the margin of this bone projects backward from the skull, giving it a hook-like appearance. In Erythrosuchus, the margin is convex and lacks a hook.

The braincase has also been studied, and possesses features that are shared with other early archosauriforms. Many of these characteristics are considered plesiomorphic, or ancestral, in archosaurs. While Erythrosuchus is not considered an archosaur, it is thought to be closely related to the last common ancestor of all archosaurs.

The hypothetical last common ancestor of archosaurs is thought to have shared many features with Erythrosuchus, many of which are found in the braincase. For example, the inner part of the otic capsule (the skeletal structure surrounding the inner ear) is not entirely ossified, or completely formed of bone. Neither is the channel for the perilymphatic duct, which is a tube that leaves the lagena.The lagena is the portion of the inner ear responsible for hearing, and is known as the cochlea in mammals (although in mammals it is coiled rather than straight). Erythrosuchus has a short lagena, which is also expected in the last common ancestor of all archosaurs.

Some features of the ankle of Erythrosuchus suggest that it was beginning to adapt toward digitigrady, or walking on toes rather than having the entire foot placed on the ground. The ankle is similar to that of Euparkeria; the ankles of both of these animals are more advanced than those of other archosauriformes.


The largest terrestrial sebecid crocodylomorph is Barinasuchus, from the Miocene of South America, which reached 9 m (30 ft) long.

Barinasuchus (meaning "Barinas crocodile," in reference to where the type material was found) is an extinct genus of sebecid mesoeucrocodylian. Its fossils have been found in middle Eocene-age rocks of the Divisadero Largo Formation of Argentina, middle Miocene-age rocks of the Ipururo Formation of Peru, and middle Miocene-age rocks of the Parángula Formation of Venezuela.

The holotype comes from Parángula Formation rocks in Barinas and consists of an incomplete articulated skull and lower jaw. Like all other sebecosuchians, it was a terrestrial carnivore with ziphodont teeth, like a theropod dinosaur. This made it a formidable predator.

Barinasuchus is the largest sebecosuchian (preserved part of the type specimen skull is 700 millimetres (28 in) long), and is the first sebecosuchian known from Venezuela. Fossils from Peru previously identified as Sebecus cf. huilensis have been assigned to the type species, B. arveloi.

Barinasuchus was described in 2007 by Alfredo Paolillo and Omar Linares.







 



Тагове:   сова,   prehistoric animals,   giant animals,   reptiles,


Гласувай:
0
0



Няма коментари
Търсене

За този блог
Автор: valentint
Категория: Политика
Прочетен: 86153
Постинги: 146
Коментари: 24
Гласове: 11
Архив
Календар
«  Юни, 2017  
ПВСЧПСН
1234
567891011
12131415161718
19202122232425
2627282930