Beipiaosaurus is a genus of therizinosauroid theropod dinosaur. The discovery of Beipiaosaurus, which translates as "Beipiao lizard" after a city in China near the location of its discovery, was announced in the May 27, 1999, issue of the journal Nature. These fossils were found in the Jianshangou bed of the Yixian Formation in Liaoning Province, China, which has been dated to the Early Cretaceous period, 124.6 million years ago.[1] It is known from a single species, B. inexpectus, named for "the surprising features in this animal.".[2] A significant number of fossilized bones for this species were recovered, including: cranial fragments, a mandible, three cervical vertebrae, four dorsal vertebrae, a caudal vertebra, the scapula and scapulacoracoid, a complete forelimb, and a complete pelvis with hindlimb. A second specimen was described by Xu et al. in 2009, which preserved a complete skull as well as a significant covering of unique, elongated feathers.[3] They were small for therizinosaurs, having been about 7ft (2 meters) long and perhaps as heavy as 201lbs (91kg). It was discovered in 1996 and named in 1999. Before the discovery of Yutyrannus, it was the largest non-avian dinosaur known from direct evidence to have been feathered. Analysis of melanosomes preserved in the specimen BMNHC PH000911 imply that the neck feathers of Beipiaosaurus were brown in color.[4]
The exact classification of therizinosaurs had in the past been hotly debated, since their prosauropod-like teeth and body structure indicate that they were generally herbivorous, unlike typical theropods. Beipiaosaurus, being considered to be a primitive therizinosauroid, has features which suggest that all therizinosauroids, including the more derived Therizinosauridae, are coelurosaurian theropods, not sauropodomorph or ornithischian relatives as once believed.
Discovery[]
In 1996, a humble peasant named Li Yinxian found the fossilized bones of a dinosaur near the town of Sihyun in China. However, it wasn't until 1999 that the fossils were rediscovered, examined, and named by paleontologists Xu
Skeletal composite of IVPP V11559 and STM 31-1
Xing, Tang Zhilu, and Wang Xiaolin, and later published in an article in the Nature Magazine. The specimen was named Beipiaosaurus inexpectus, or "unexpected Beipiao lizard". At first, base on the peg-like teeth, scientists thought it was a species of prosauropod, like Plateosaurus, but when more specimens of dinosaurs with long necks, big bodies, extending arms with clawed hands, and theropod-like feet were discovered, they realized Beipiaosaurus was part of a genus of dinosaurs now called therizinosaurs. What makes Beipiaosaurus special, though, is scientists now know that, based off its primitive appearance, therizinosaurs actually evolved from coelurosaurs like dromaeosaurids (Raptors) rather than sauropodomorphs or ornithischians as thought of previously. It also, from very well-preserved specimens, clued us in that therizinosaurs more than likely had feathers covering their whole bodies.
The holotype of Beipiaosaurus inexpectus was discovered in the Early Cretaceous deposits of the Liaoning Province in China. The specimen was discovered near Beipiao County, hence its namesake.[2] The quarry at Liaoning is world-renowned for its excellent preservation of feather impressions from a variety of feathered dinosaurs.
Remains of the holotype[]
The holotype specimen unearthed was composed, of a few skull elements, including a mandible, as well as 3 cervical vertebrae, 4 dorsal vertebrae, 1 caudal vertebra, scapula and scapulacoracoid, complete forelimb, and a complete pelvis with hind limb.[2]
Description[]
Beipiaosaurus measured 2.2 meters (7.3 ft) in length, and is among the largest known feathered dinosaurs.[2]Beipiaosaurus had a toothless beak with cheek teeth. More advanced therizinosaurids have four functional toes, but the feet of Beipiaosaurus' have reduced inner toes, showing that the derived therizinosaurid condition may have evolved from a three-toed therizinosauroid ancestor. The head was large relative to other therizinosaurs, with the lower jaw over half the length of the femur.[2]
Feathers[]
Feather impressions on the left arm from the holotype on display at the Paleozoological Museum of China
Skin impressions from the type specimen of B. inexpectus indicated that the body was covered predominately by downy feather-like fibers, similar to those of Sinosauropteryx, but longer, and are oriented perpendicular to the arm. Xu et al., who described the specimen, suggested that these downy feathers represent an intermediate stage between Sinosauropteryx and more advanced birds (Avialae).[2]
Unique among known theropods, Beipiaosaurus also possessed a secondary coat of much longer, simpler feathers that rose out of the down layer.[5] These unique feathers (known as EBFFs, or elongated broad filamentous feathers) were first described by Xu et al. in 2009, based on a specimen consisting of the torso, head and neck. Xu and his team also found EBFFs in the original type specimen of B. inexpectus, revealed by further preparation.
The holotype had the largest proto-feathers known of any feathered dinosaur, with the author and paleontologist Xing Xu staing: "Most integumentary filaments are about 50 mm in length, although the longest is up to 70 mm. Some have indications of branching distal ends.".[2]
Diagram illustrating feather evolution stages. Beipiaosaurus falls within stage 1 and stage 2
The EBFFs differ from other feather types in that they consist of a single, unbranched filament. Most other primitive feathered dinosaurs have down-like feathers made up of two or more filaments branching out from a common base or along a central shaft. The EBFFs of Beipiaosaurus are also much longer than other primitive feather types, measuring about 100-150 millimeters (4-6 inches) long, roughly half the length of the neck. In Sinosauropteryx, the longest feathers are only about 15% of the neck length.
The EBFFs of Beipiaosaurus are also unusually broad, up to 3 mm wide in the type specimen. The broadest feathers of Sinosauropteryx are only 0.2 mm wide, and only slightly wider in larger forms such as Dilong. Additionally, where most primitive feather types are circular in cross section, EBFFs appear to be oval-shaped.
None of the preserved EBFFs were curved or bent beyond a broad arc in either specimen, indicating that they were fairly stiff. They were probably hollow, at least at the base.
Life restoration
In a 2009 interview, Xu stated: "Both [feather types] are definitely not for flight, inferring the function of some structures of extinct animals would be very difficult, and in this case, we are not quite sure whether these feathers are for display or some other functions." He speculated that the finer feathers served as an insulatory coat and that the larger feathers were ornamental, perhaps for social interactions such as mating or communication.[5]
Appearance[]
Like other therizinosaurs, Beipiaosaurus had a long neck and small head for reaching into trees easier, giving itself an almost sauropod look. It also had very long arms and wicked claws on each of its fingers for stripping trees of their bark and leaves, and also likely were used for defense against predators. Its body was rather stout, likely ending in a sort of pot-belly, but was much leaner than that of other larger, more evolved therizinosaurs. Beipiaosaurus jaws started out with a beak in the front and then had peg-like cheek teeth more towards the back, for stripping vegetation more efficiently. However, the teeth weren't very good for sauropod look. It also had very long arms and wicked claws on each of its fingers for stripping trees of their bark and leaves, and also likely were used for defense against predators. Its body was rather stout, likely ending in a sort of pot-belly, but was much leaner than that of other larger, more evolved therizinosaurs.
It grew to be about 7.5 feet (2.6 meters) long, 4 feet (1.3 meters) long, and 100 pounds (45 kilograms) in weight, making it quite small in terms of therizinosaur and dinosaur standards. Nevertheless, its discovery was an important find in the fossil record for piecing together therizinosaur evolution. As far as we know, Beipiaosaurus had the longest feathers of any known dinosaur, and during the mating season were likely used to attract mates like modern birds do. Being a more primitive therizinosaur also sets it apart from other species related to it, such as features like a slender body and shorter neck. Its legs were also relatively longer than in relatives such as Therizinosaurus, suggesting it was a faster runner. Beipiaosaurus is also unique in its feet; while other, more evolved therizinosaurs had three toes, it had four that were all functional, and gives another hint that it likely evolved from maniraptoran dinosaurs. Some people think that it may have had an appearance similar to a Panda.
Classification[]
Schematic comparison of the ilium of Beipiaosaurus (in B) and other related therizinosaurs
As with all therizinosaurs, the classification of Beipiaosaurus is controversial. Like other therizinosaurs, Beipiaosaurus had stump-like teeth that resembled those of prosauropods, and the inferred body posture of Beipiaosaurus implies an upright, herbivorous lifestyle, as seen in the image to the right. it has also been suggested that the long "claws" of Beipiaosaurus were used to strip branches and other foliage down from trees. Beipiaosaurus has been classified as a basal therizinosaur, due to Beipiaosaurus' feet having reduced inner toes. Other, more derived therizinosaurs, have four functional toes. This suggests that other, more derived therizinosaurs, may have evolved from a three-toed therizinosauroid ancestor, such as Beipiaosaurus.
Paleobiology[]
Phosphatised soft tissues in non-avian maniraptoran dinosaurs and a basal bird. Beipiaosaurus in b and g
In 2018, McNamara and colleagues discovered the fossilised remains of skin flakes from numerous feathered dinosaurs from the Jehol Biota and some bird species using scanning electron microscope on the preserved feather impressions. The analyzed fossil taxa consisted of Confuciusornis, Beipiaosaurus, Microraptor and Sinornithosaurus. For Beipiaosaurus, the specimen STM 31-1 was analyzed.
By exposing the skin flakes under an electron microscope they found corneocytes, which are cells rich in keratin. In order to make comparisons with extant feathered dinosaurs, they analyzed several bird taxa such as Anas, Lonchura and Taeniopygia and found similar cell structures, but the fossil dinosaur corneocytes were more densely packed with keratin and lacking lipids (fat), suggesting that Beipiaosaurus and co-analyzed taxa did not get as warm as modern birds, mainly because they were ground-dwelling animals not able to fly. In the case of the primitive birds Confuciusornis, they could not fly at all for long periods. In modern birds these structures, with the addition of fats, help to regulate body temperature during active flight.
In addition, the identified corneocytes structures seem to indicate that non-avian dinosaurs had a similar way of shedding skin to extant birds and mammals. Unlike many reptiles alive today (lizards or snakes) which shed their skin as a single piece or as several large pieces, Beipiaosaurus and other non-avian dinosaurs shed their skin as dandruff, like Confuciusornis, modern birds or mammals.
JPInstitute.com Description[]
Beipiaosaurus had the longest feathers of any dinosaur yet found. Classified as a plant-eater, it is thought that these dinosaurs would also have fed on insects a great deal of the time. It is considered a bird-like dinosaur and shared a number of features that are now found on modern birds.
Described in 1999, Beipiaosaurus is one of a few known bird-like dinosaurs. It came from the famous shale quarries of Liaoning, China, which are well known for producing many incredibly detailed fossils of small dinosaurs and birds. Most of the bird/dinosaur relationship studies are conducted on specimens from this quarry, as unique ecological conditions preserved even the soft parts of the animals that died at this site. These unusual conditions allowed for the perfect preservation of feathers.
Beipiaosaurus remains are fragmentary, but they do show that it was bipedal like other therizinosaurs and that it had sharp, curved hand claws and protofeathers.
Dinosaur Field Guide Description[]
Beipiaosaurus ("Beipiao lizard"') is one of the therizinosaurs, a very strange group of theropods. Therizinosaurs (also known as "sloth dinosaurs") have very short, heavy feet, wide bellies, long necks, big claws, and small heads at the end of long necks. Their teeth are leaf shaped, like those of plant-eating dinosaurs, which makes them plant-eating members of the family of meat-eating dinosaurs! Beipiaosaurus is known from one partial skeleton from the Yixian Formation in northeastern China.The volcanic ash that formed the mud of this formation was so fine-grained that it preserved very small details of the animals buried in it. Fossils show that Beipiaosaurus's body was covered with long, slender filaments. These filaments were a sort of protofeather, a body cover that eventually evolved into true feathers in birds and some other dinosaurs (such as Caudipteryx). The protofeathers of Beipiaosaurus might have been used for insulation or for display, or for both.
Fun Facts[]
Beipiaosaurus is the smallest known therizinosaur. Its giant relative Therizinosaurus was almost as big as T-rex and hau claws almost 5 feet (90 cin) long!
Trivia[]
Beipigosaurus is the first therizinosaur known to have protofeathers.
Gallery[]
Appearance in other media[]
Jurassic Park[]
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Read more Beipiaosaurus on Jurassic Park Wiki |
The Land Before Time[]
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Read more Beipiaosaurus on Land Before Time Wiki |
Links[]
http://web.archive.org/web/20031008032333fw_/http://www.jpinstitute.com/dinopedia/dinocards/dc_beipi.html https://web.archive.org/web/20080723140602/http://kids.yahoo.com/dinosaurs/129--Beipiaosaurus
References[]
- ↑ Zhou, Z. (2006). "Evolutionary radiation of the Jehol Biota: chronological and ecological perspectives." Geological Journal, 41: 377-393.
- ↑ 2.0 2.1 2.2 2.3 2.4 2.5 2.6 Xu, X., Tang, Z-L., and Wang, X-L. (1999). "A therizinosauroid dinosaur with integumentary structures from China." Nature, 399(6734): 350-354.
- ↑ Xu X., Zheng X.-t. and You, H.-l. (2009). "A new feather type in a nonavian theropod and the early evolution of feathers." Proceedings of the National Academy of Sciences (Philadelphia), 106(3): 832-834. doi: 10.1073/pnas.0810055106
- ↑ https://www.academia.edu/6860358/Melanosome_evolution_indicates_a_key_physiological_shift_within_feathered_dinosaurs
- ↑ 5.0 5.1 Bryner, Jeanna (2009). "Ancient Dinosaur Wore Primitive Down Coat." http://www.foxnews.com/story/0,2933,479875,00.html