Dryptosaurus

Credit: Gabriel Ugueto.

*Dryptosaurus* is an extinct genus of dryptosaurid dinosaur that lived in New Jersey during the Late Cretaceous.

## History

*Dryptosaurus* was about 7.5 meters long and was first made popular by a painting by Charles R. Knight, though it has fallen back into obscurity. Edward Drinker Cope (1866) first named it as Laelaps, but Othniel Charles Marsh (1877) renamed it because the name was preoccupied by a mite. This makes it one of the first known theropods.

## Description

*Dryptosaurus* appears to have had proportionally longer arms when compared to derived tyrannosaurids. It also may have had three digits on each hand. However, Brusatte et al. (2011) find a similar phalnge shape between it and derived tyrannosaurids, instead finding that Dryptosaurus may have had 2 functional digits. Each digit had a large claw that were about an inch long. Reduction in the hdands suggests that it did not occur in uniform. It may have used both the jaws and hands while hunting, ANSP 9995 is a fragmentary adult individual preserving a fragmentary right maxilla, a fragmentary right dentary, a fragmentary right surangular, lateral teeth, 11 middle-distal caudals, both humeri, phalanges I-1, II-2 and an ungual of the left hand, shafts of both public bones, a scrappy right ischium, a left femur, a left tibia, a left fibula, a left astragalus and the midshaft of metatarsal III. The neurocentral sutures are sealed in every caudal, which proves it is mature. AMNH FARB 2438 is a left metatarsal IV that is likely from the holotypic individual. The femur is 3% longer than the tibia, the longest manual ungual phalanx is 176 millimeters long, and the proximal of metatarsal IV suggests an arctometatarsalian foot (present in advanced tyrannosauroids). Brusatte et al. (2011) find the following autapomorphies: a reduced humerus, a large hand, a strong mediolateral expansion of the ischial tubercle and an ovoid fossa on the medial of the femoral shaft and proximal to the medial condyle, which is anteriorly demarcated by the mesiodistal crest and medially by the novel crest. A proximomedially-reaching ridge at the anterior of the fibula and proximal directly to the iliofibularis tubercle and the lateral condyle lip at the lateral being prominent and overlapped from the proximal of the calcaneum and metatarsal IV with a proximally-flat shaft with a semiovoid cross section that is wider mediolaterally then it is long anteroposteriorly are all present.

## References

* https://www.smithsonianmag.com/science-nature/how-dryptosaurus-got-its-name-68864150/?no-ist
* https://digitallibrary.amnh.org/handle/2246/6117
* https://www.researchgate.net/publication/281043562\_The\_Anatomy\_of\_Dryptosaurus\_aquilunguis\_Dinosauria\_Theropoda\_and\_a\_Review\_of\_Its\_Tyrannosauroid\_Affinities
* https://web.archive.org/web/20070310231340/http://www.vertpaleo.org/jvp/17-561-573.html
* https://www.tandfonline.com/doi/abs/10.1080/00222936708679723
* https://archive.org/details/mesozoicvertebra0000unse/page/10/mode/2up
* https://www.gbif.org/dataset/13c8f8f0-3ea5-4a40-afb1-5292f8380faa
* https://www.researchgate.net/publication/318485947\_Teihivenator\_gen\_nov\_a\_new\_generic\_name\_for\_the\_Tyrannosauroid\_Dinosaur\_Laelaps\_macropus\_Cope\_1868\_preoccupied\_by\_Koch\_1836
* https://www.biodiversitylibrary.org/part/238885
* https://repository.si.edu/handle/10088/22800
* https://digital.lib.ecu.edu/ncpi/view/10005
* https://www.researchgate.net/publication/233904673\_A\_New\_Genus\_And\_Species\_Of\_Tyrannosauroid\_From\_The\_Late\_CretaceousMiddle\_Campanian\_Demopolis\_Formation\_Of\_Alabama
* https://www.app.pan.pl/article/item/app20110141.html