Episode 318 is all about Genyodectes, The first theropod described from South America.
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In this episode, we discuss:
News:
- An extinction event in the Early Jurassic may have led to the dominance of Eusauropods, including the recently named Bagualia source
- The new Triassic theropod Erythrovenator was found in Southern Brazil source
- In Rapid City South Dakota, Dinosaur Hill is getting renovated to become more accessible source
- New graphic novel coming out next July called Operation Dragon featuring a Japanese-trained dinosaur army source
The dinosaur of the day: Genyodectes
- Ceratosaur theropod that lived in the Cretaceous in what is now Chubut Province, Argentina (Cerro Barcino Formation)
- Type species is Genyodectes serus
- Genus name means “jaw bite”
- Species name means “late”
- Holotype includes part of the snout (premaxillae, parts of the maxillas, right and left dentary, teeth, and more)
- Not well preserved, some of it is articulated
- Carnivorous
- Had large, protruding teeth, similar to Ceratosaurus (long and curved)
- The way the teeth are arranged in the premaxilla is unique, and only seen in Ceratosaurus. The difference between Genyodectes and Ceratosaurus is Ceratosaurus had three teeth in each premaxilla, and Genyodectes had four
- Estimated to be 20.5 ft (6.25 m) long and weigh 1740 lb (790 kg)
- Described in 1901 by Sir Arthur Woodward
- Santiago Roth collected the fossils for the Museo de La Plata
- Some quotes from Sir Arthur Woodward’s description:
- “All of these teeth are much broken”
- “Unfortunately, nothing is known of the jaws which bore similar teeth during the Cretaceous period in the Northern hemisphere; but it seems probably that the completion of the tooth-sockets and the paucity of successional teeth in Genyodectes are characters indicating that it was one of the latest and most specialized members of its race.”
- Second non-avian dinosaur described from South America, after Loncosaurus
- First known theropod described from South America
- For a while thought to be a nomen dubium, because fossils were so fragmentary, but a redescription in 2004 by Oliver Rauhut found it to be valid
- At different points thought to be megalosaurid, tyrannosaurid, theropoda incertae sedis, and abelisaurid. But Oliver Rauhut’s re-exaxmination removed the holotype from its “artificial matrix” and found it to not have abelisaurid and tyrannosaurid traits, but to have many neoceratosaurian traits, and found it probably came from the Cerro Castaño Member of the Cerro Barcino Formation (before, not completely clear where the fossils had been found, but known they were found in red sandstone)
- Oliver Rauhut reprepared the type material. He wrote: “As is the case with the bones of the skull, the dentaries are rather massive”
- Teeth in the premaxilla were close together and in “an overlapping en-echelon pattern” (parallel formation at a slanted angle)
- The right side of the skull was slightly deformed but not the left
- Had long maxillary tooth crowns, that were longer than the “minimal height of the dentary” (also only seen in Genyodectes and Ceratosaurus, so far)
- Helps show early diversification of neocertosaurs in South America
- Fossils are at the Museo de La Plata in Argentina
- Other dinosaurs that lived around the same time and place included titanosaurs Patagotitan and Chubutisaurus, and carcharodontosaurid Tyrannotitan
Fun Fact: From a phylogenetic standpoint, humans are cynodonts. Cynodonts and other animals ruled the Triassic before Dinosaurs stole their thunder.
