Herrerasaurus
The name Herrerasaurus means Herrera's Lizard. It was named after the rancher who first discovered the fossils. The Herrerasaurus is one of the earliest dinosaurs, having lived approximately 231.4 million years ago (mya). It is believed to have roamed the woodlands of what is now the country of Argentina.
The basic theropod skull form can already be seen in Herrerasaurus along with a similar dental arrangement. As a predator Herrerasaurus probably focused its hunting upon small reptiles as well as the smaller dinosaurs. The long legs of Herrerasaurus would have seen it easily able to keep pace with the smaller dinosaurs, and it was probably one of the few predators that were able to catch them. Larger reptiles like the rhynchosaur Hyperodapedon were more heavily built and may have also been attacked, although its stocky build may have meant that smaller juveniles were more likely to be taken.
A skull feature of Herrerasaurus that is usually not seen in other dinosaurs is that of a sliding lower jaw. This sliding jaw can be seen in some other reptiles though so this feature is more probably a case of individual specialisation rather than an evolutionary characteristic. This sliding action may have allowed Herrerasaurus to rake its teeth through prey as well as possibly to more easily hold on to small prey as it struggled in between its jaws.
Speed and agility seem to have been key to the hunting strategy of Herrerasaurus which probably would have been seen exhibiting such behaviour as moving amongst the undergrowth and quickly snatching up animals that were scared out of hiding. The immediate clues to this are the legs which have a proportionately short femur (upper leg bone) while the lower leg bones are very long. Additionally Herrerasaurus had a digitigrade stance which meant that it walked on its toes so that the metatarsal foot bones actually served to extend the length of the leg, increasing the stride which in turn increased the top speed of Herrerasaurus. The feet also show a development towards a three toed foot as while the first and fifth digits are still present only one had a (reduced) claw, something which indicates that they were not used to gain extra traction on the ground. In later dinosaurs these toes would become reduced to the point that they were vestigial (present but no longer serving any purpose). Also the pubis on Herrerasaurus points backwards, something that is seen in dromaeosaurid dinosaurs like Deinonychus as well as birds, and further suggests reliance upon agility. The arms are also quite long and may have been used for holding onto prey.
A similar dinosaur to Herrerasaurus that is also from the same location is Sanjuansaurus.
The name Herrerasaurus means Herrera's Lizard. It was named after the rancher who first discovered the fossils. The Herrerasaurus is one of the earliest dinosaurs, having lived approximately 231.4 million years ago (mya). It is believed to have roamed the woodlands of what is now the country of Argentina.
The basic theropod skull form can already be seen in Herrerasaurus along with a similar dental arrangement. As a predator Herrerasaurus probably focused its hunting upon small reptiles as well as the smaller dinosaurs. The long legs of Herrerasaurus would have seen it easily able to keep pace with the smaller dinosaurs, and it was probably one of the few predators that were able to catch them. Larger reptiles like the rhynchosaur Hyperodapedon were more heavily built and may have also been attacked, although its stocky build may have meant that smaller juveniles were more likely to be taken.
A skull feature of Herrerasaurus that is usually not seen in other dinosaurs is that of a sliding lower jaw. This sliding jaw can be seen in some other reptiles though so this feature is more probably a case of individual specialisation rather than an evolutionary characteristic. This sliding action may have allowed Herrerasaurus to rake its teeth through prey as well as possibly to more easily hold on to small prey as it struggled in between its jaws.
Speed and agility seem to have been key to the hunting strategy of Herrerasaurus which probably would have been seen exhibiting such behaviour as moving amongst the undergrowth and quickly snatching up animals that were scared out of hiding. The immediate clues to this are the legs which have a proportionately short femur (upper leg bone) while the lower leg bones are very long. Additionally Herrerasaurus had a digitigrade stance which meant that it walked on its toes so that the metatarsal foot bones actually served to extend the length of the leg, increasing the stride which in turn increased the top speed of Herrerasaurus. The feet also show a development towards a three toed foot as while the first and fifth digits are still present only one had a (reduced) claw, something which indicates that they were not used to gain extra traction on the ground. In later dinosaurs these toes would become reduced to the point that they were vestigial (present but no longer serving any purpose). Also the pubis on Herrerasaurus points backwards, something that is seen in dromaeosaurid dinosaurs like Deinonychus as well as birds, and further suggests reliance upon agility. The arms are also quite long and may have been used for holding onto prey.
A similar dinosaur to Herrerasaurus that is also from the same location is Sanjuansaurus.
Technosaurus
Technosaurus is in simple terms a mess. Described in 1984 by Sankar Chatterjee from an astralgus (ankle bone), a dorsal (back) vertebrae, two lower jaws and a premaxilla, Techonosaurus was heralded as the earliest ornithischian (bird hipped) dinosaur of the time. Then in 1991another palaeontologist named Paul Sereno re-examined the fossils, a study that would be the beginning of the doubt in the validity of Technosaurus being the earliest known ornithischian dinosaur.
First Sereno found that both the vertebrae and astralgus were unidentifiable, and thus could not be used to define the genus. Sereno was also of the opinion that the premaxilla and one of the jaws belonged to a hatchling prosauropod, a kind of saurischian (lizard hipped) dinosaur. A 2007 review by Irmis et al took things even further. It was agreed that the vertebra and astralgus should be removed from the genus, but the reviewers also found no characteristics in the skull and jaw material that could definitely identify them as being dinosaurian. Instead the new review considered the remains to be similar to another archosaur called Shuvosaurus, in fact one of the jaw fragments was considered to actually be from a Shuvosaurus.
Currently Technosaurus only has a premaxilla and a jaw fragment assigned to the genus. Although sometimes tentatively assigned to the dinosauriformes, Technosaurus is now often just described as an indeterminate archosaur. Despite this, Technosaurus has been noted as sharing some similarities with another archosaur called Silesaurus.
Guaibasaurus
Guaibasaurus is known from fairly good remains, though the skull is unknown. When first described, Guaibasaurus was considered to be a potential theropod dinosaur, though later a similarity with the primitive sauropodomorph dinosaur Saturnalia was noted, and now Guaibasaurus is usually seen as a very primitive sauropodomorph dinosaur.
Euskelosaurus
The Euskelosaurus was a massive prosauropod dinosaur. It was in existence in the late Triassic period about 220 to 205 million years ago. It was amongst the largest dinosaurs of its time. Its discovery played an important role in understanding the development of the gigantic sauropods of the Jurassic period.
The Euskelosaurus grew up to 30 to 35 meters in length and weighed about 1400 to 1600 kilos. These dimensions were much larger than other prosauropods. It was slow moving and most likely an herbivore.
The remains of the Skelosaurus have been discovered in the southern regions of the African continent. It is expected to have inhabited the whole of Africa in its heyday.
Ruehleia
The Ruehleia was a prosauropod dinosaur whose remains were discovered in Germany. It was extant about 215 to 205 million years ago in the Norian age of the Triassic period of the Mesozoic era.
The size of the Ruehleia was moderate to large as compared to other prosauropods. It adult size is estimated to be about 6 to 8 meters in length. Its body weight could have been between 500 to 1000 kilos. Its height could possibly have been 2 to 3 meters.
The fossils of the Ruehleia were initially thought to belong to the Plateosaurus. This was due to the discrepancies in understanding the sacrum of the remains. But further investigations revealed that they belonged to a completely different species of dinosaur.
Etymology
The name Ruehleia was coined by paleontologist Peter Galton. The fossils were originally thought belong to the Plateosaurus and they were reassigned by Galton in 2001. The nomenclature was chosen to honor the fossil collector Ruehle von Lilienstern who excavated the fossils in 1952. The suffix '-ia' indicates ‘of Ruehle’ or ‘belonging to Ruehle’.
The binomial name Ruehleia bedheimensis points out to the town of Bedheim from where Lilienstern hailed.
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