In our 82nd episode, we had the pleasure of speaking with Dr. David Hone, a Lecturer in Zoology at Queen Mary University of London. He has a blog called Archosaur Musings where he talks about dinosaurs and pterosaurs, and he has contributed to the naming of more than a dozen animals (mostly dinosaurs). His research focuses primarily on how dinosaurs behaved, and he recently published a book titled The Tyrannosaur Chronicles: The Biology of the Tyrant Dinosaurs.
Episode 82 is also about Ouranosaurus, an herbivore with long neural spines, similar to Spinosaurus.
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In this episode, we discuss:
- The dinosaur of the day: Ouranosaurus
- Name means “brave lizard”
- The word ourane is Arabic and means courageous, bold. And some nomads in Niger, where it was found, call local monitor lizards ourane
- Type species is Ouranosaurus nigeriensis
- Species name refers to Niger, the country where it was found
- Paleontologist Philippe Taquet named Ouranosaurus in 1976
- Taquet found the bones in January 1965, and fossils were excavated in 1966
- Taquet first used the name Ouranosaurus in July 1972 at a public presentation of the skeleton
- Two specimens have been found, in 1965 and 1972
- Holotype is of a nearly complete skeleton and a skull, and is mounted in the Nigerien capital Niamey (can see a cast at the Museum national d’histoire naturelle)
- Taquet’s memoir, called “Dinosaur Impressions: Postcards from a Paleontologists,” said the the first Ouranosaurus specimen “was placed in the National Museum of Niger in Niamey, inaugurated by the president of the National Assembly of that country, Boubou Hama. A small Niger girl, very timid and cute, with her plaited braids, dressed like an ouranosaur in silk colored like the Niger flag, presented the president with a pair of scissors to cut the ribbon across the entry door.”
- Herbivore that lived in the early Cretaceous in what is now Africa
- Taquet said it weighed about 4 tons and was 23 ft (7 m) long, but Greogry S. Paul said in 2010 it was probably 2.2 tons and 27 ft (8.3 m) long
- Had a short tail
- Had a short, flexible neck
- Had thumb claws or spikes on each hand, and broad hoof-like second and third fingers, which means it may have been able to walk on them (may have been quadrupedal)
- Had narrow feet with three toes each
- Had pretty short forelimbs (about 55% the length of the hindlimbs)
- Could also walk bipedally. Femur was longer than the tibia, and where the muscles connected to the base of the tail was weakly developed so it was probably not a fast runner
- Skull was as high as it was wide
- Skull was about 36 in (67 cm) long, and had a long, flat heat and a long snout
- Had small rounded horns in front of its eyes
- Had a low bump between the nose and eye on each side of its face, though why it was there is not clear (for mating displays? socialization?)
- Probably spent a lot of time quadrupedal for grazing on low-lying plants
- Probably browsed low vegetation
- Had a broad beak, somewhat like a duck billed hadrosaurid (used to pull soft, leafy plants from out of water)
- Nostrils were high on the snout (easier to breathe while eating low vegetation)
- Had a wide beak and cheek teeth, and had two sets of teeth (one set of replacement teeth)
- Probably ate tough plants, as well as fruits and seeds
- Could eat tougher plants with its cheek teeth too (but not too tough, because of weak jaw bite)
- Had weak jaw muscles
- Had a large sail on its back with long neural spines (looked somewhat like a Spinosaurus)
- Spinosaurus and Ouranosaurus lived millions of years apart
- Somewhat similar to Dimetrodon, but had thicker spines than Dimetrodon
- Spines probably covered in skin
- Supporting spines were thick and flat, and the spines at the back were stiff and bound together with ossified tendons, and the tallest spines were over the forelimbs
- The tallest spines were nearly 2 ft (0.6 m) tall
- Spines may have been used for thermoregulation, display, or as a hump with muscle tissue or fat (like a camel), used to store energy
- Hump in case of a low rainy season?
- In 1997, Dr. Jack Bowman Bailey from Western Illinois University said that Ouranosaurus‘ spines looked like a modern bison’s. But not everyone agrees, since Ouranosaurus may not have needed to store fat
- Jack Bowman Bailey’s paper was published in the Journal of Paleontology in 1997 and was called “From Neural Spine Elongation in Dinosaurs: Sailbacks or Buffalo-Backs?
- Bailey wrote that Ouranosaurus and Spinosaurus and other long-spined dinosaurs had more bison-like humps than sails, because they lived in tropical climates and probably didn’t need a sail for thermoregulation, and that humps were probably used to store energy, help sheild from heat, help with long distance migration, and help with conserving energy when nesting/brooding
- Ouranosaurus lived in a river delta
- Other dinosaurs included Lurdusaurus and Nigersaurus, as well as fish, pterosaurs, and sharks
- Possible predator was Suchomimus, primarily a fish eater but also lived near the river delta (could have gone after juveniles)
- Another potential threat was Carcharodontosaurus
- Also Sarchosuchus, a giant crocodile
- Originally Ouranosaurus was considered to be part of Iguanodontidae (similar thumb spike) but now it’s considered to be part of the clade Hadrosauroidea, as a basal hadrosauroid
- Hadrosauroidea is a clade of dinosaurs that includes the duck billed dinosaurs (hadrosaurids, and dinosaurs more closely related to them than Iguanodon)
- Fun fact: Humans have two types of sex chromosomes X and Y, every embryo gets an X from the egg and if the sperm has an X the resulting XX is a female, while an XY makes a male. Some animals (including birds) have a ZW scheme where the egg alone determines the gender. And unlike humans the “homogametic sex” is the male with a ZZ and the female is a ZW. Crocodiles and Alligators do not have sex chromosomes and the gender is instead determined by temperature (with higher temperatures typically resulting in more males). And since all modern birds have ZW genes, it’s likely that non-avian dinosaurs did too.
For those who may prefer reading, see below for the full transcript of our interview with Dr. David Hone:Continue Reading …