Episode 438: What Triassic dinosaurs ate. Plus a new Torosaurus specimen, a new spinosaurid find that includes arms, and we connect dinosaurs to Emmy Noether

News:

• The earliest dinosaurs had surprising diets source
• Ornithischians evolved to eat plants in many different ways source
• A new Torosaurus specimen has been found source
• Scientists have discovered a new spinosaurid source
• The Natural History Museum in London recently discovered an agate crystal in its collections is a titanosaur egg source
• Crystal Palace Dinosaurs recently got more funding source
• Filmmaker Danny Donahue made a short sci-fi film called Hell Creek source

Sponsors:

You can dig up real dinosaur bones this summer with Colorado Northwestern Community College! Join them for a two week immersive field paleontology experience digging up dinosaur bones from the Jurassic period in Northwest Colorado. There are two scheduled digs: May 27–June 11 and July 1–July 16. There are also two concurrent immersive lab techniques programs available. Get all the details and register online at cncc.edu/dinodig

The dinosaur of the day: Mymoorapelta

• Nodosaurid ankylosaur that lived in the Late Jurassic in what is now Colorado and Utah, U.S. (Morrison Formation)
• Nodosaurids don’t have tail clubs
• Looks similar to Nodosaurus, heavily armored and covered in scutes, with spikes coming out of its sides,
• Walked on all fours, had a long tail, low to the ground, small elongated head
• Estimated to grow up to 9.8 ft (3 m) long
• Estimated to weigh between about 660 and 1230 lb (about 300 to 560 kg)
• Smallest known four-legged dinosaur from the Morrison Formation and one of the smallest ankylosaurs
• Skull hasn’t been described in detail but looks similar to Gargoyleosaurus, which is also from the Morrison Formation
• Gargoyleosaurus was named in 1988
• Had a narrow snout, and triangular skull
• Had two large horns on the brow and two horns on the cheek
• Had small, leaf-shaped teeth
• Had 13 ribs and four sacral ribs (rib-like structures around the sacrum, which is connected to the pelvis)
• Had short limbs
• “The proportions of the ulna and ilium in Mymoorapelta suggest it had a stance reminiscent of that observed in stegosaurs with its high narrow hips and short powerful forelimbs”, according to Kirkland and Carpenter, who named the dinosaur
• Had a somewhat flexible tail (more flexible than ankylosaurid tails that were strongly fused)
• Tail vertebrae were longer than they were wide
• Had spikes on the tail
• Tail may have been for defense or for fighting other nodosaurids
• Had large spiky osteoderms on its sides and back
• Five armor types found: long spines with a hollow base and a long groove up the side; thin, triangular plates with a narrow, asymmetric hollow base; small bladelike spines with a rounded, solid base; isolated, flat scutes; and scutes fused into a single sheet of armor
• Large spine probably was at the base of the neck and pointed outward
• Thin triangular plates were probably attached lower down the body and to the tail
• Part of the sacral shield preserved, including a small piece of armor that has one large osteoderm surrounded by smaller osteoderms and looks flower-like
• Had keeled osteoderms, or bosses, and elevated knobs as well on the sacral shield
• Back and tail was covered in small osteoderms in between larger plates of armor (based on comparisons to Sauropelta)
• Lived in a semiarid environment with wet and dry seasons, and had floodplains
• Had a high relative bite force, based on its jaw joint
• Probably a low browser and probably a selective feeder because of its narrow snout
• Probably ate cycads and conifers
• Type and only species: Mymoorapelta maysi
• Described by Jim Kirkland and Kenneth Carpenter in 1994
• Genus name means “Mygatt’s shield”
• Named in honor of Vannetta Moore and Pete and Marilyn Mygatt, who found the Mygatt-Moore Quarry where the fossils were found
• Species name is in honor of Chris Mays, president of the Dinamation International Corporation and Society, who funded excavating the quarry
• Quarry site found in March 1981 by Peter Marilyn Mygatt and John D. and Vanetta Moore “while on an excursion in the high desert of western Colorado”, according to Kirkland and Carpenter
• Fossils first found in 1990
• Quarry is “interpreted as an attritional accumulation of abundant dinosaur remains at a permanent water hole,” according to Kirkland and Carpenter
• Could be animals were killed coming down the water hole to drink, animals died of thirst or/and starvation at the water hole during drought, or animals became trapped in the mud along the margin of the water hole when seeking water during dry periods when the water hole was small
• Lots of evidence of scavenging and/or subsequent trampling, so any specific cause of death for any particular animal is unclear
• Mymoorapelta is the third most common dinosaur in the Mygatt-Moore Quarry (Allosaurus is the most common, then Apatosaurus)
• First known Late Jurassic ankylosaur from North America, and one of the earliest known nodosaurids
• Holotype includes a left hip bone (with bitemarks), vertebrae, ribs, limb bones, and lots of osteoderms
• Fused vertebral column, so holotype is considered to be an adult
• “Although it is obvious the animal was fed upon, it can not be determined if the animal was killed by a predator or simply scavenged”, according to Kirkland and Carpenter
• Bite marks found on Mymoorapelta may be from a very large Allosaurus (unusually large), or some other large carnivorous dinosaur
• Over 160 bones have been found, and they were scattered over 27 yards (25 m) of the 1600 sq ft (150 sq m) quarry
• Although disarticulated, “one of the most complete Jurassic ankylosaurids described to date” and “the smallest adult, quadrupedal dinosaur yet identified in the Morrison Formation”, according to Kirkland and Carpenter
• Also found a small dinosaur egg (less than 4 in or 10 cm in diameter) with “unique ornithischian-style microstructure). Egg was associated with the ankylosaur
• Because no other ornithischians are known from the quarry, and none of the saurischian dinosaurs (other than maybe a small theropod) from the area were small enough to have laid such a small egg, Kirkland and Carpenter wrote: “we suspect that egg may have been aborted on the death of the ankylosaur. Although speculative, if the egg belongs to the ankylosaur, it suggests that the death of the animal may have been sudden, perhaps by the animal being trapped in the mud and then killed or at least scavenged”
• Kirkland and others referred a partial skeleton to Mymoorapelta in 1998, found in Cactus Park, Colorado (fossil was still being prepared at that time)
• Partial skeleton included vertebrae, chevrons (from under the tail vertebrae), sacrum (part of the pelvis), and lots of armor, including parts of the sacral shield that covered the top of the pelvis
• More bones have been found at the quarry since, including a nearly complete skull, and nearly all parts of the body except the pubis and femur (a hip bone and leg bone)
• Fossils are at the Dinosaur Journey Museum of Western Colorado in Fruita, Colorado
• Another specimen was found near Hanksville, Utah which includes more osteoderms, ribs, a vertebra, and femur
• Another Mymoorapelta specimen was found in 2014, in the Hanksville-Burpee Quarry, which is a “sauropod-dominated bonebed” according to Katie Tremaine and others
• Eight known specimens of Mymoorapelta, and four of them found in sauropod localities
• Other dinosaurs that lived around the same time and place include Apatosaurus, Allosaurus, Ceratosaurus, and possibly Nanosaurus
• Other animals that lived around the same time and place include lots of snails and fish

Fun Fact:

You can visit rivers on Earth that dinosaurs once swam in, fished in, and drank from.

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