Episode 545: Are Silesaurs Dinosaurs? Silesaurs are definitely dinosauromorphs (close relatives of dinosaurs) but were they true dinosaurs?

News:

• There’s a new silesaurid, Itaguyra occulta, whose name means “Stone Bird” in Tupi—a language from Southern Brazil where it was found source
• A new large femur found in Zambia may have been from a 10ft (3m) long silesaur—quite large for the source
• Probable silesaur arm and leg bones from the Late Triassic were described from what is now Texas source

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The dinosaur of the day: Planicoxa

• Iguanodontian that lived in the Early Cretaceous in what is now Utah, U.S. (Poison Strip Sandstone Member of the Cedar Mountain Formation)
• Looked a lot like Iguanodon, but smaller
• Estimated to grow up to 15 ft (4.5 m) long and weigh 990 lb (450 kg)
• Had a bulky body, a long tail, a long head
• Probably had a beak
• Could probably walk on all fours or on two legs when necessary
• Partial skeletons of several individuals found
• Fossils found include hips, thigh bones, shin bones, and vertebrae, as well as rib fragments, parts of the arm, and parts of the feet
• Fossils found in the spring of 1998 by a team of volunteers from the Denver Museum of Natural History
• Quarry where it was found is called Tony’s Bone Bed
• Found with other dinosaurs, including an adult and juvenile sauropod, and a theropod
• Fossils in good condition but no articulated bones
• Possible the dinosaurs accumulated in the bone bed over a span of time, maybe during a dry season with not much water
• Type species is Planicoxa venenica
• Described in 2001 by Tony DiCroce and Kenneth Carpenter
• Holotype is a left ilium (hip bone)
• Hips were well preserved
• Genus name means “flat hip” and refers to the flat appearance of the hips (ilium)
• Species name means “poison” and refers to the Poison Strip Sandstone Member, where it was found
• A second species was named in 2008 by Carpenter and Wilson (renamed Camptosaurus depressus to Planicoxa depressus). It also had the flat hip feature, but in 2011 it was named as a new genus, Osmakasaurus
• Other dinosaurs that lived around the same time and place include the sauropod Venenosaurus, the nodosaur Gastonia, and Utahraptor
• Other animals that lived around the same time and place include turtles, amphibians, fish, and mammaliaforms

Fun Fact:

There are 17 named silesaurs, but at least 12 of them have been or are currently being debated as to whether they are silesaurs.

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