The Abrosaurus was a dinosaur that lived in the middle Jurassic period of the Mesozoic era. The timeline of its existence can be fixed at 170 to 160 million years ago. This would be the approximately in the Bajocian to the Callovian ages.
The Abrosaurus was an Asian dinosaur. Its fossils were discovered in China. It has certain features that match prosauropods, but most scientists agree that it was a sauropod dinosaur.
The size of the Abrosaurus was relatively small as compared to the other Jurassic sauropods. Its length was about 28 to 32 feet and its weight was approximately 4000 to 4500 kilos. Some of the largest sauropods of Jurassic period weighed as much as 30,000 kilos. But these dinosaurs were present on the earth later than the Abrosaurus. Most likely, giant sauropods like the Apatosaurus evolved from dinosaurs like the Abrosaurus.
The Abrosaurus was a herbivorous dinosaur, like other sauropods. Herbivores far exceeded carnivorous dinosaurs in the Jurassic period.
The word ‘abros’ is a Greek word that translates to ‘fragile’ or ‘delicate’ in English. The word ‘sauros’ means ‘lizard’ in English. Hence, the name ‘abrosaurus’ indicates ‘a lizard which is fragile’. The skull of the Abrosaurus was very flimsy, made up of small pieces of bones. Hence it was deemed a delicate dinosaur.
The binomial name Abrosaurus dongpoi was chosen to honor the Chinese poet Su Dongpo.
The christening of the remains of the Abrosaurus was done by Ouyang Hui.
Discovery of fossils
- The fossils of the Abrosaurus were discovered in the Dashanpu Quarry in 1984. This quarry is located in Sichuan, China. This location lies in the Lower Shaximiao Formation.
- Many other Jurassic dinosaur fossils were recovered along with those of the Abrosaurus.
- A separate set of remains were later discovered in the same area which were thought to belong to the Abrosaurus. They consisted of parts of the skull and few other spinal bones. There are no research papers, however, connecting these bones with the Abrosaurus, they are not officially included amongst the known remains of the Abrosaurus.
Nature of fossils
There was a district crest present along the nasal bone of the Abrosaurus. The nares were present on either sides of this crest. The Abrosaurus is depicted with this ridge on its head in all the museums in the world where they have reconstructed figures of the Abrosaurus.
The classification of the Abrosaurus is not universally accepted. It was first classified under clade Camarosauromorpha. But as the remains were studied more carefully, scientists began to question this premise. Today, it is considered a sauropod dinosaur belonging to clade Macronaria.
- Ouyang Hui originally named the fossils Abrosaurus gigantorhinus. This name was chosen because of the size of the dinosaur.
But the research work submitted by Hui in 1986 lacked certain criteria required by the international nomenclature committee and hence the species was not officially recognized.
- Later in 1989, Hui submitted a revised paper, this time naming the fossils Abrosaurus dongpoensis. But the rules of nomenclature dictate that the suffix ‘ensis’ can only be used to denote a site; Dongpo was a person.
- Hui again changed the species name to dongpoi, a name acceptable to the international agency.
Current location of fossils
The fossils of the Abrosaurus are currently held by the Zingong Dinosaur Museum.
The Shaximiao Formation
The Shaximiao Formation is a part of the expansive Dashanpu Formation of China. The bones of the Abrosaurus were found in the Lower Shaximiao Formation.
The Dashanpu Formation consists of four groups. Out of these, only the Upper and the Lower Shaximiao groups have yielded fossils. The other two, the Zhenchuchong and the Ziliujing Formation have yet been investigated in detail.
Many dinosaurs have been excavated in this Formation. They include the Dashanpusaurus, the Gongxianosaurus, the Abrosaurus, the Gasosaurus, the Sinraptor, etc.
Ouyang Hui is a contemporary vertebrate paleontologist. He has received his doctorate from the Chengdu University of Science and Engineering in Sichuan. He has worked comprehensively in the Dashanpu Formation alongside many of his comtemporaries.
- The Abrosaurus was larger dinosaur, weighing 4 to 5 tons. But this size was modest compared to the other sauropod dinosaurs. It was about 9 to 10 meters in length from head to tail.
- The neck of the Abrosaurus was very long.
- Its head was almost geometric in shape and was marked by the typical crest.
- The legs of the Abrosaurus were short and stout.
- The Abrosaurus had a long and thin tail.
Habits and habitat
It walked on all four legs. It is not known whether the Abrosaurus could support its weight on its hind legs to increase its reach.
The habitat of the Abrosaurus consisted of wooded areas and grasslands that were green all throughout the year.
Related and coexisting species
The Abrosaurus is believed to be intimately related to the Camarasaurus. It is possible that the two dinosaurs may have had immediate common ancestors.
Many dinosaurs are thought to have coexisted with the Abrosaurus. These include the Shunosaurus, Omeisaurus, Huayangosaurus, etc. The Yangchonosaurus may have been a predator of the Abrosaurus as it had the size and strength to challenge the Abrosaurus.
The Abrosaurus was one of the largest dinosaurs of its time. But despite of its great size, it was still very small as compared to other sauropods. It features were very unique and resembled many camarasaurid dinosaurs.
Its discovery was very important in understanding the diversity of the Asian dinosaurs. Although its exact classification is debatable, its features link sauropods and prosauropods. This has shown that Asia could have been host to a large variety of Triassic prosauropods and Jurassic sauropods.