Dryptosaurus (Tearing lizard)
Dryptosaurus (Tearing lizard)
Named By : Othniel Charles Marsh - 1877 (Originally named by Edward Drinker Cope in 1866 as Laelaps aquilunguis)
Diet : Carnivore
Size : Estimated 6.5- 7.5 meters long
Type of Dinosaur : Large Theropod
Type Species : D. aquilunguis (type)
Found in : USA
When it Lived : Late Cretaceous, 84-65 million years ago
Dryptosaurus (/,drIptoU’so:r@sDRIP-toh-SOR@s) is one of the genus of tyrannosauroids which was alive for 70 millions of years ago (mya) during the second portion of the Cretaceous period in New Jersey. Dryptosaurus was a massive bipedal, ground-dwelling, carnivore that grew to 7.5 meters (25 feet) in length. Though it’s not well-known beyond academia, a renowned artwork of the genus by Charles R. Knight made Dryptosaurus among the most popular dinosaurs of the past despite its scant fossil records. The first time it was identified by Edward Drinker Cope in 1866 and then changed to Dryptosaurus after Othniel C. Marsh in 1877. Dryptosaurus was among the first dinosaurs that were known to scientists.
Dryptosaurus is believed to be 7.5 metres (25 feet) long , and to have been weighing 1.5 tonnes (1.7 shorter tons) however this estimate is based on fragments of the remains of one. As with its cousin Eotyrannus, Dryptosaurus seems to have had arms with a length of about 3.5 metres when compared to more evolved tyrannosaurs like Tyrannosaurus. The hands are also large , were believed to have three fingers. Brusatte et al. (2011) However, they found a general similarity in the form of the phalanges of Dryptosaurus and Tyrannosaurids that are related to it. They also noted that Dryptosaurus could have only two digits that were functional. The fingers of Dryptosaurus were equipped with an eight-inch claw shaped like a talon. The morphology of its forelimbs suggests that the reduction of forelimbs in tyrannosauroids might not have taken place in a consistent manner. Dryptosaurus could have utilized both arms and jaws as weapons while searching, capturing, and processing prey.
The specimen of the type is a skeleton fragment belonging to one adult. ANSP 9995 comprises an elongated right maxilla, a fragmentary right dental left surangular, left and right lateral teeth, eleven middle-distal cervical vertebrae, both the right and left humeri, three manual-phalanges of the left hand (I-1 II-2, I-1 and an unnatural) as well as The shafts and tendons of right and left pubic bones as well as a fragmentary right-hand femur, the left ischium as well as the left tibia the left fibula, left astragalus and a midshaft portion from the metatarsal III. The ontological maturation of the holotype person is confirmed through the evidence that sutures of the neurocentral region are closed in all the caudal vertebrae. AMNH FARB 2438 consists of the left metatarsal IV. They could be from the same person as the Holotype.
The left maxilla, which is fragmentary, retains the three alveoli complete, while the fourth is only partially. They were able determine that Dryptosaurus was a ziphodont dentition. The form of the alveolus found on the anterior part of the fragment indicates that it was home to teeth that were smaller and less round than others and an incisiform tooth that is typical in the tyrannosauroids. The disarticulated teeth found are transversely small and well-serrated (17-18 teeth/cm) and curving. The femur is just 33% larger that the tibia. The longest ungual phalanx manual discovered measured 176 millimeters (6.9 millimeters) long. The pattern of the proximal region of the metatarsal IV suggests Dryptosaurus possessed an arctometatarsalian feet which is a unique characteristic shared by other tyrannosauroids like Albertosaurus and Tyrannosaurus that is, where the metatarsal 3 is “pinched” between the second and fourth metatarsals.
According to Brusatte et al. (2011), Dryptosaurus can be distinguished by these characteristics consisting of the reduced in humerus (humerus: Femur ratio of 0.375) as well as a larger hand (phalanx I-1:femur ratio = 0.200) as well as the large medialateral expansion of the ischial tubercle that is 1.7 times the size of the shaft immediately distal to it and there is an oval fossa on the medial side of the femoral shaft in the medial condyle’s proximal region that is delineated from the front by the mesiodistal crest and medially by a novel crest the presence of a proximomedially inclining edge on the front of the fibula that is immediately close to the iliofibularis tubercle and the lip that is on the lateral side of the condyle’s lateral side of the astragalus is noticeable and it is located over the surface that is proximal to the calcaneum. Metatarsal IV is seen by a plane shaft in the proximal region which results in an oval cross section which is significantly larger medially than it is anteroposteriorly.