Episode 255 is all about Nyasasaurus, a 240 million year old dinosauriform that may be the earliest known dinosaur.
Interview with Christopher DiPiazza, a science teacher, paleo artist, and creator of the popular site, Prehistoric Beast of the Week. He covers a different prehistoric animal (nearly) every week, with an original painting he creates, a photograph of the fossil, and whenever possible, input from a paleontologist who worked on that animal. Follow him on twitter or @ChrisDPiazza or Instagram.
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In this episode, we discuss:
News:
- A new early cretaceous carcharodontosaurian, Siamraptor, was discovered in Thailand source
- Rebecca Jensen shared her database and map of Dinosaur National Monument with us source
- In St. George, Utah, carnivorous dinosaur footprints have been found from roughly 200 million years ago source
- The Las Vegas Natural History Museum announced their paleontology team found 240 million year old vertebrate tracks source
- The Dickinson’s Badlands Dinosaur Museum has a new find, a 77 million year old tyrannosaur source
- New fossils on display, including a juvenile Triceratops, adult Triceratops, and a hadrosaur source
- Maximus, a 70 million year old 3m long dinosaur recently sold for for about $227,000 source
- Smithsonian Mag published a list of spots to dig for dinosaur bones source
- In Sacramento, California, a man in a Allosaurus costume stopped by a Sacramento City Hall source
- Supergirl star, Melissa Benoit, shared a photo of herself riding a dinosaur and hugging a T. rex source
The dinosaur of the day: Nyasasaurus
- Dinosauriform that lived in the Middle Triassic in what is now Tanzania (Manda Formation)
- May be the earliest known dinosaur
- Described in 1956 by Alan Charig in a doctoral thesis (but not officially described until 2013)
- Holotype found in the 1930s by Francis Rex Parrington, along with cynodonts, dicynodonts, and rhynchosaurs
- Alan Charig was one of Francis Parrington’s PhD students
- Charig first described them as “Specimen 50b”
- In 1967 Charig used the name Nyasasaurus parringtoni, in a review of Archosauria, but didn’t provide any description so it was considered a nomen nudum (also his dissertation was never published)
- In 2013 Sterling Nesbitt, Paul Barrett, Sarah Werning, and Christian Sidor published a new description (and include Alan Charig posthumously) to give Nyasasaurus parringtoni a valid name
- Alan Charig died in 1997
- Type species is Nyasasaurus parringtoni
- Genus name means “Lake Nyasa lizard”
- Genus name refers to Lake Nyasa and the species name is in honor of Parrington
- Before Nyasasaurus, the oldest known dinosaur was about 231 million years old and found in Argentina (Herrerasaurus)
- Nyasasaurus is about 10-15 million years older than that dinosaur
- Type specimen is a partial skeleton 6.5-9.8 ft (2-3 m) long, and includes a right humerus (upper arm bone), three partial sacral vertebrae and three presacral vertebrae
- A second specimen was found that has three cervical vertebrae and two posterior presacral vertebrae, but it wasn’t clear until Nesbit et. al described the specimen in 2013 that the two were definitively the same species
- Weighed between 45 to 135 lb (20 to 60 kg)
- No skull bones found, so unclear what it ate
- Not clear if it was bipedal or quadrupedal
- Probably had a long neck and tail
- Hard to classify because of fragmentary fossils found, but it is within Archosauria and within Dinosauriforms, the group that includes birds, non-avian dinosaurs, and some non-dinosaurian groups that lived in the Triassic
- Thought to be one of the earliest dinosaurs (earliest known dinosaur)
- Nesbitt and team did a systematic comparison of Nyasasaurus fossils with close relatives and found a number of characteristics that made Nyasasaurus a true dinosaurs, including three vertebrae in the sacrum (connects the spine to the pelvis) compared to ancestors that only had two, it grew rapidly, based on histology, and it had a broad bone crest on its upper arm which attached should muscles to the upper arm bone (crest was more than 30% of the bone’s length, and is known as an elongated deltopectoral crest); however, the arm bone was fragmentary so it’s hard to know for sure if it reallly was more than 30% of the bone’s length, which made Nesbitt and his team not 100% sure Nyasasaurus was a dinosaur (but at the very least it would have been a very close relative)
- Arm bone had lots of bone cells and blood vessels in the bone tissues, which indicates rapid growth
- Showed Nyasasaurus grew as fast as other early dinosaurs but not as fast as later dinosaurs
- Nyasasaurus in Tanzania helps support the idea of a southern Pangaean origin for dinosaurs
- When early dinosaurs like Eoraptor were in Argentina 10 million years after Nyasasaurus existed, there were already diverse groups of dinosaurs, which meant dinosaurs must have been evolving for a while before that
- Proposed that dinosaurs evolved and gradually became dominant (instead of there being an explosion of dinosaurs, as previously thought), but not all scientists agree (especially if it turns out Nyasasaurus was just a close relative of dinosaurs instead of a dinosaur)
- Oldest known silesaurid (closest known relatives of dinosaurs), Asilisaurus kongwe, was also in the Manda Beds in Tanzania, which shows dinosaurs and their close relatives co-existed
- The type specimen is at the Natural History Museum in London
- The second, referred specimen is in the South African Museum in Cape Town
Fun Fact: Sauropods may not have slept much if at all. At least not the way that we sleep.
