Episode 552: What Dinosaurs Ate. Plus, a new species of megaraptor, Joaquinraptor casali, is one of the most complete ever found.

News:

• A new megaraptor, Joaquinraptor casali, may have died in the middle of eating a crocodilian source
• Analyzing skull mechanics can tell us a lot about different theropod dinosaur feeding strategies source
• The alvarezsaur Bannykus ate meat (instead of maybe insects) source
• A poor sauropod got gnawed on by a theropod (probably) source
• The gut contents of a subadult Diamantinasaurus shows it was not a picky eater and it did not chew its food source
• A closer look at coprolites found in the Lameta Formation in India show they were likely pooped out by an omnivorous animal, and not a titanosaur (as previously thought) source

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The dinosaur of the day: Dromaeosauroides

• Dromaeosaurid theropod that lived in the Early Cretaceous in what is now Denmark (Jydegaard Formation), and also possibly what is now England
• Only know it from two teeth
• As a raptor, walked on two legs, covered in feathers, had a long(ish) head, a long tail, and had a large sickle claw on the second toes of each of its feet
• One of the oldest known raptors in the world (Jydegaard Formation is about 140 million years old)
• First known dinosaur from Denmark, and the only one with a scientific name
• Found on the island of Bornholm in the Baltic Sea
• First tooth found in 2000, and the second tooth found in 2008
• Teeth are curved and finely serrated
• Holotype tooth is 0.85 in (21.7 mm) long
• Estimated to be 7 to 10 ft (2 to 3 m) long and weigh about 88 lb (40 kg)
• Teeth are similar to Dromaeosaurus teeth
• Compared to a Dromaeosaurus tooth, holotype is about 25% bigger, which is how we got the body size estimate
• Denticles in the teeth are different in Dromaeosaurus compared to Dromaeosauroides (denticles in Dromaeosauroides are smaller even though the tooth is bigger and there are more denticles)
• Also, Dromaeosaurus lived 60 million years after Dromaeosauroides
• Not many dinosaur remains have been found in Scandinavia, and they’re hard to find in Denmark, because there was a lot of sea around there in the Mesozoic
• The Swedish province Scania, has more fossils, including dinosaurs
• Danish island Bornholm was part of the same landmass as Scania, so they have similar geology, and the southwestern part of the island is where the only Danish dinosaur remains have been found
• In the 1990s and early 2000s (until 2005) there was a group of people who maintained geological sites on Bornholm, known as the Fossil Project. In September 2000, Christiansen and Bonde taught a field course at the site called “The Hunt for Danish Dinosaurs” and during the course, student Eliza Jarl Estrup found a theropod tooth
• When the first tooth was found, local TV happened to be filming the course
• Found in a gravel pit
• The tooth discovery was considered to be like “finding a needle in a haystack”
• Tooth likely came from the front of the jaw
• Front part of the holotype is worn, which means the dinosaur shed its tooth
• Possible the tooth was even larger in life (since it was a shed tooth and there is wear and damaged parts on the surface)
• Tooth found with a juvenile sauropod tooth, so lived with sauropods
• Since finding the tooth, dinosaur tracks and teeth have been found around the same area
• In 2008, Jens Kofoed found the second tooth, in the same location
• Named in 2003 by Per Christiansen and Niels Bonde
• Type and only species is Dromaeosauroides bornholmensis
• Genus name means “Dromaeosaurus-like”
• The genus name Dromaeosaurus means “swift” or “running lizard”
• Species name means “from Bornholm”
• In 2008, Johan Lindgren and others found Dromaeosauroides to be an indeterminate dromaeosaur
• Bonde disagreed, and said because the teeth were different from other dromaeosaurs it should be considered valid
• Some scientists in 2010 suggested theropod teeth from the Late Jurassic and Early Cretaceous that look similar to raptor teeth may be from small tyrannosauroids instead
• Possible that Dromaeosauroides teeth were also found in England (thought to belong to Nuthetes)
• Nuthetes is a coelurosaurian theropod, either a dromaeosaurid or tyrannosauroid
• Lived in the Early Cretaceous in what is now England and France
• Only known from teeth and jaw fragments
• But some of the teeth might belong to Dromaeosauroides (the larger ones, that are 15 to 18 mm long)
• Coprolites found, with fish remains, that may be from Dromaeosauroides
• If the coprolites are from Dromaeosauroides, would mean it could catch fish, possibly using its sickle claw (like “spear fishing”)
• Two partial coprolites found, and both were dark in color and you could see “abundant prey remains” on the surfaces, according to a 2012 study
• One coprolite was a fragment from a cylindrical specimen, with lots of bone fragments and fish scales (diameter of 2.5 cm or almost 1 in)
• The other was also cylindrical (4.4 cm or 1.7 in long)
• One of the coprolites has evidence of coprophagous organisms (means they eat feces/dung)
• Feces has evidence it was either dropped on land, a sandy beach, then partly eaten by insects and deposited in the lagoonal water, or dropped in coastal water, drifted to the beach, infested by insects, and then buried in the lagoon
• Holes in the poop look like burrows from small insects (most likely dung beetles and fly larvae). Left two deep burrows as well as small pits and grooves
• Coprolites were long and cylindrical with a smooth surface, similar in shape to coprolites found in England that are considered to be from crocodiles or small theropods
• Did not come from a sauropod, because there are fish bones and scales in it
• Did not come from sharks or other fish, because their poop is usually coiled or spiral-shaped
• Seems unlikely to come from a crocodylian because of the fish scales and bone fragments (modern crocodylians have an effective digestive system, that dissolves bone, though we don’t know when crocodylians evolved such strong stomach acid)
• Could be from turtles (right shape, and in some modern turtles we see undigested fish bones in the feces)
• No plesiosaurs found in the formation, and pterosaurs are uncertain, though they could be the ones who produced the poop (this is speculative)
• Size, shape, and prey content in the poop is “consistent with coprolites from turtles and theropod dinosaurs”
• Lived in a coastal lagoon environment with lots of vegetation
• Other animals that lived around the same time and place include sauropods (possibly titanosaurs), sharks, other fish, turtles, lizards, crocodiles, and either birds or pterosaurs (based on thin bone fragments found)

Fun Fact:

Hypercarnivorous crocodyliforms probably ate dinosaurs. source

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