Post by dinosauria101 on Sept 7, 2019 17:14:50 GMT 5
Aerosteon riocoloradense
Aerosteon was an approximately 9 metres (30 ft) long, 2 metric ton bipedal carnivorous dinosaur that lived approximately 84 million years ago during the Santonian stage.
The holotype specimen, MCNA-PV-3137 consists of a single tooth (which may instead belong to an abelisaurid), some cranial bones, a number of partial or complete vertebrae from the neck, back, and sacrum, several cervical and dorsal ribs, gastralia, furcula (wishbone), left scapulocoracoid, left ilium, and left and right pubes. The incomplete fusion of some of its bones indicate that it was not quite fully mature.
Aerosteon did not initially appear to belong to any of the three groups of large theropods that were known to have inhabited the southern continents during this time (namely the Abelisauridae, Carcharodontosauridae or Spinosauridae). Sereno suggested that it might be related to the allosauroid radiation of the Jurassic period, and this was supported in subsequent studies that recognized a clade of late-surviving, lightly built, advanced allosauroids with large hand claws similar to the spinosaurs, called the Megaraptora, within the allosaur family Neovenatoridae.[3] A later analysis has placed Megaraptora, including Aerosteon, within the Tyrannosauroidea.[4] Megaraptorans have since been also considered as non-tyrannosauroid basal coelurosaurs in some analyses.[5][6]
Abelisaurus comahuensis
As only the skull is known, it has proven difficult to provide a reliable size estimate of Abelisaurus. It has transpired that abelisaurids have relatively short heads. In 2010, Gregory S. Paul estimated its body length at ten metres (32 ft 10 in), its weight at 3 tonnes (3 long tons; 3 short tons).[4] In 2016, its length was estimated to be 7.4 metres (24 ft 3 in) in a comprehensive analysis of abelisaur size.[5]
Skull length was estimated at 859 millimetres (33 3⁄4 in) in 1985. The skull is relatively deep. Although there are no bony crests or horns, like those found in some other abelisaurids, such as Carnotaurus, rough ridges on the snout and above the eyes might have supported some kind of crest made out of keratin, which would not have become fossilized. The skull roof is thickened. There are also very large fenestrae (window-like openings) in the skull, which are found in many dinosaurs and reduce skull weight. One of these is a large triangular antorbital fenestra in the side of the snout. The eye socket behind it is rather high. It is constricted in the middle by bony projections of the lacrimal bone in the front and the postorbital bone at the rear. The eye was located above the constriction. Behind the eye socket a large triangular infratemporal fenestra is present. Its form reflects a strong forward inclination of the back of the skull.[1]
The front snout bone, the praemaxilla, bore four relatively small teeth. The maxilla behind it had at least seven, but perhaps as many as thirteen, larger teeth.[1]
Credit to Wikipedia; C. Abraczinskas
Aerosteon was an approximately 9 metres (30 ft) long, 2 metric ton bipedal carnivorous dinosaur that lived approximately 84 million years ago during the Santonian stage.
The holotype specimen, MCNA-PV-3137 consists of a single tooth (which may instead belong to an abelisaurid), some cranial bones, a number of partial or complete vertebrae from the neck, back, and sacrum, several cervical and dorsal ribs, gastralia, furcula (wishbone), left scapulocoracoid, left ilium, and left and right pubes. The incomplete fusion of some of its bones indicate that it was not quite fully mature.
Aerosteon did not initially appear to belong to any of the three groups of large theropods that were known to have inhabited the southern continents during this time (namely the Abelisauridae, Carcharodontosauridae or Spinosauridae). Sereno suggested that it might be related to the allosauroid radiation of the Jurassic period, and this was supported in subsequent studies that recognized a clade of late-surviving, lightly built, advanced allosauroids with large hand claws similar to the spinosaurs, called the Megaraptora, within the allosaur family Neovenatoridae.[3] A later analysis has placed Megaraptora, including Aerosteon, within the Tyrannosauroidea.[4] Megaraptorans have since been also considered as non-tyrannosauroid basal coelurosaurs in some analyses.[5][6]
Abelisaurus comahuensis
As only the skull is known, it has proven difficult to provide a reliable size estimate of Abelisaurus. It has transpired that abelisaurids have relatively short heads. In 2010, Gregory S. Paul estimated its body length at ten metres (32 ft 10 in), its weight at 3 tonnes (3 long tons; 3 short tons).[4] In 2016, its length was estimated to be 7.4 metres (24 ft 3 in) in a comprehensive analysis of abelisaur size.[5]
Skull length was estimated at 859 millimetres (33 3⁄4 in) in 1985. The skull is relatively deep. Although there are no bony crests or horns, like those found in some other abelisaurids, such as Carnotaurus, rough ridges on the snout and above the eyes might have supported some kind of crest made out of keratin, which would not have become fossilized. The skull roof is thickened. There are also very large fenestrae (window-like openings) in the skull, which are found in many dinosaurs and reduce skull weight. One of these is a large triangular antorbital fenestra in the side of the snout. The eye socket behind it is rather high. It is constricted in the middle by bony projections of the lacrimal bone in the front and the postorbital bone at the rear. The eye was located above the constriction. Behind the eye socket a large triangular infratemporal fenestra is present. Its form reflects a strong forward inclination of the back of the skull.[1]
The front snout bone, the praemaxilla, bore four relatively small teeth. The maxilla behind it had at least seven, but perhaps as many as thirteen, larger teeth.[1]
Credit to Wikipedia; C. Abraczinskas
