Episode 20 is all about Dysalotosaurus, an herbivore with one of the earliest known viral infections.

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In this episode, we discuss:

• The dinosaur of the day: Dysalotosaurus lettowvorbecki, which means “uncatchable lizard”
• It’s a dryosaurid iguanodontian (herbivore)
• It lived in the late Jurassic
• Dysalotosaurus fossils have been discovered in the Tendaguru Formation in Tanzania
• The Berlin Museum of Natural History discovered and excavated Dysalotosaurus fossils, when it was still German East Africa
• Rudolf Virchow named Dysalotosaurus in 1919
• All Dsyalotosaurus fossils were found in one quarry, and between 1910-1913 they found 14,000 bones. Also in the area they discovered other dinosaurs, including the sauropods Giraffatitan and Dicraesosaurus, the stegosaur Kentrosaurus, and the theropod Elaphrosaurus
• The name lettowvorbecki came from German national hero, General Paul Emil von Lettow-Vorbeck. He fought in WWI. in East Africa, and was known for his guerrilla warfare tactics. He commanded 3,000 Germans and 14,000 Africans (local soldiers known as Askaris), and though at the time black soldiers were often discriminated against, von Lettow-Vorbeck treated all his soldiers the same. He was fluent in Swahili, and according to one historian, “It is probably that no white commander of the era had so keen an appreciation of the African’s worth not only as a fighting man but as a man.”
• von Lettow-Vorbeck was never defeated, but he surrendered after he heard about the Armistice, in November 1918. His German soldiers were repatriated, but the Askaris were put in camps. Lettow-Vorbeck worked hard to have the Askaris be treated decently
• Back in Germany, Lettow-Vorbeck opposed the Nazis, and when Hitler offered him a position in 1935, he declined. He was often harassed by the Nazis, and the reason he survived the Nazi years is because he was so popular as a WWI German hero
• Unfortunately many Dysalotosaurus fossils were destroyed in WWII during bombing raids (so know some of the best records of it are via drawings
• Of the fossils that survived, only one still has about 50% of the skeleton
• It used to be considered to be a species of the genus Dryosaurus, but now it’s in its own genus (Dysalotosaurus)
• Dysalotosaurus was medium sized and ran on two legs
• Dysalotosaurus was precocial, meaning it was born in an advanced state and able to take care of itself at a young age, and became sexually mature after only ten years
• It’s unclear how quickly it grew, but it could reach the size of a large kangaroo
• In 2011, two paleontologists Florian Witzmann and Oliver Hampe and their colleagues found that some of the Dysalotosaurus bones with deformations were probably caused by a viral infection, making it the “oldest evidence of viral infection known to science”
• It is similar to Paget’s disease of bone, which has abnormal bone destruction and regrowth (may be why it’s hard to determine how it grew)
• First evidence of viral infection, ever
• Scientists have found thousands of Dysalotosaurus bones at varying stages of maturity, possibly from one herd
• Both juvenile and adult fossils of Dysalotosaurus have been found, which allowes Dr. Stephan Lautenschlager and Dr. Tom Hubner to study the species’ brain, at two different growth stages
• The smallest Dysalotusaurus specimen was 0.7 meters long and the largest was 5 meters long
• They used CT scanning and 3D imaging to reconstruct the brain and inner ear of a 3 year old and a 12 year old Dysalotosaurus
• They published their findings in the Journal of Evolutionary Biology
• They learned that juveniles had strong hearing and cognitive processes but a lot changed as they grew older, to help adapt to their environment
• Younger Dysalotosaurus had shorter snouts and larger eye sockets (probably cuter), also only 20 teeth versus 26 teeth as adults. The teeth became wider in older dinosaurs, and juveniles had three upper teeth that were slimmer than the rest (adults did not have this), which may mean juveniles were monivores and adults were purely herbivores
• The study helps show how parts of the brain developed in dinosaurs, but more research is needed to establish a pattern of brain development
• Dryosaurids lived during the Mid-Jurassic and early Cretaceous period, in Africa, Europe and North America
• They were primitive iguanodonts
• They were medium-sized, with long legs, small forelimbs, and small, short snouts
• They had soft-tissue above their eyes, which made them look like they were frowning (as seen in modern birds of prey)
• Dryosaurids were bipedal, with three toes on each foot (but only representing digits II, III, and IV, not the first toe, or “hallux”)
• They look somewhat similar to ornithopods, such as Hypsilophodon, so they used to be considered “hypsilophodonts.” Now they are classified as part of the Iguanodontia group, which is not close to Hypsilophodon (Dryosaurids did not have premaxillary teeth, which means they only used their beak to bite off plants
• The first dryosaurids were found in the 1870s in North America, and then later more were found in Africa in the early 1900s, then in Europe in the 1970s (the dryosaurid fossils were found earlier in Europe but had been misclassified)
• Fun fact: The first dinosaur was found in North America in 1854, by Ferdinand Vandiveer Hayden while he was exploring the upper Missouri River. He found some teeth, that Joseph Leidy classified as part of Trachodon, Troodon, and Deinodon, in 1856