Episode 399: The many uses of melanin. Maria McNamara teaches us about melanin, melanosomes, and what they can (and can’t) tell us about dinosaur colors.

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Interview:

Maria McNamara, a paleobiologist and professor of paleontology at the School of Biological, Earth and Environmental Sciences at University College Cork. Follow her on twitter @MariaMcN_palaeo and see more details on Ireland’s fossil heritage here.

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The dinosaur of the day: Dyoplosaurus

• Ankylosaur that lived in the Late Cretaceous in what is now Alberta, Canada (Dinosaur Park Formation)
• Looked like other ankylosaurs, with armor covering its body, walked on all fours, had a tail club
• Estimated to be 13 to 15 ft (3.9 to 4.5 m) long and weigh 3300 to 5500 lb (1500 to 2500 kg)
• Relatively small, with a long, narrow tail club
• Tail club had ten vertebrae that formed the handle and several osteoderms that formed the knob
• Tail club knob was longer than it was wide
• Probably wasn’t born with the tail club, and formed it later in life (possible that the tail club found in Dyoplosaurus was still growing)
• In 2009, Victoria Arbour did a study (CT scans of clubs referred to Dyoplosaurus and Euoplocephalus) on the impact force of ankylosaur tail club strikes and found Dyoplosaurus couldn’t generate enough force to puncture bone (knob was too small)
• May mean the knobs weren’t primarily for defense. May have been used also for display
• Had slender, bladelike neural spines
• Had triangular osteoderms on the sides of the front of the tail
• Sacral fenestrae (holes in the pelvis) formed a butterfly-like arrangement
• Herbivorous
• Type species is Dyoplosaurus acutosquameus
• Described by William Parks in 1924
• Genus name means “double armored lizard”
• Species name means “sharp scale”
• Closely related to Scolosaurus and Anodontosaurus
• Holotype found in 1919 by Levi Sternberg, near Red Deer River
• Holotype includes a partial skull roof, jaw fragments with teeth, osteoderms, skin impressions, vertebrae, tail club, lower leg bones, ribs
• Holotype was mostly the back half of the dinosaur, with the front half mostly missing
• Holotype was probably an almost fully mature individual
• Holotype skull was originally comprised of several scattered fragments, but a lot of the fragments were discarded in 1924 because they could not be articulated (the rest made up an incomplete front of the skull roof)
• Parks wrote, the tail club was “distinctly different from any previously described and, as far as I am aware, from any that have been collected.”
• Three teeth were preserved with the fragments, but Parks only illustrated the one he considered the best in his description
• Tooth has since been lost, though the other two teeth are still around
• Gilmore in 1930 referred a skull to Dyoplosaurus, based on similarities in the teeth and having osteoderms on the skull, but he said the skull looked a lot like Euoplocephalus tutus
• Gilmore also said Parks’ illustration of the Dyoplosaurus tooth in 1924 was inaccurate (tooth looked more nodosaurid than ankylosaurid) and proposed corrections, including his own illustrations of the teeth
• Two specimens referred to Dyoplosaurus have partial tail clubs
• Evgeny Maleev named a second species in 1956: Dyoplosaurus giganteus, based on a large specimen with caudal vertebrae, foot bones, and osteoderms including a partial tail club knob
• Fossils found in Mongolia (Nemegt Formation)
• Maleev said it had similar vertebrae to Dyoplosaurus acutosquameus but was different because it was bigger
• In 1977 it was reassigned to Tarchia by Tumanova, as Tarchia gigantea
• In 2014, Victoria Arbour and others found the holotype to not have diagnostic features (had features in common with all ankylosaurines), and considered it to be a nomen dubium
• Also said the differences in size could be from individual variation or ontogeny
• Walter Coombs synonymized Dyoplosaurus, Scolosaurus, and Anodontosaurus with Euoplocephalus in 1971 (one of the Dyoplosaurus jaws was the same as other Euoplocephalus specimens)
• Coombs, when synonymizing, said the variability in ankylosaur skulls from Dinosaur Park Formation and Horseshoe Canyon Formation meant either each specimen was its own species or there was only one species of ankylosaur, and he decided there was only one species
• Then in 2009, Victoria Arbour and others redescribed Dyoplosaurus and found it to be valid (hips, vertebrae, and especially the tail is different enough), and suggested the synonymy was because of the fragmentary nature of the specimens of Euoplocephalus
• Wrote, “it might be necessary to look beyond traditional cranial characters in order to accurately appraise the number and nature of various ankylosaurid taxa”
• Arbour and others proposed the variation in skulls meant there were multiple types of ankylosaurs
• Euoplocephalus was also found in a younger formation (Horseshoe Canyon Formation), a couple million years younger than the formation where Dyoplosaurus was found (Dinosaur Park Formation)
• In 2011, Thomson and others confirmed Dyoplosaurus was valid
• In 2011, Tetsuto Miyashita and others looked at the skulls of Euoplocephalus, and mentioned that there are no skull characters that separate Dyoplosaurus from Euoplocephalus (features that make them unique are in the pelvis and feet), so it’s possible some skulls referred to Euoplocephalus may be Dyoplosaurus
• Lived in an area with frequent flooding
• Other dinosaurs that lived around the same time and place include the ankylosaurs Edmontonia, Euoplocephalus, and Scolosaurus, the ceratopsid Chasmosaurus, hadrosaurs Corythosaurus, Gryposaurus, and Parasaurolophus, the tyrannosaur Gorgosaurus, the dromaeosaur Hesperonychus, the troodontid Latenivenatrix, and the caenagnathids Caenagnathus and Chirostenotes

Fun Fact:

Dinosaurs can help us detect contamination in the environment.

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