Episode 461: Four new theropods including abelisaurids and a deinocheirid! A pair of abelisaurids from the latest Cretaceous of Morocco, a new deinocheirid from Early Cretaceous Japan, and a long-legged possibly flightless bird from Jurassic of China

News:

• A new Early Cretaceous deinocheirid from Japan, Tyrannomimus fukuiensis, helps fill in the very early evolution of dinosaurs that eventually led to Deinocheirus source
• Paleontologists found two new abelisaurids in Morocco—helping to fill in details of the mostly unknown latest Cretaceous of Africa source
• There’s a new early bird-like dinosaur (an anchiornithid avialan) with “bizarre” long legs source

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The dinosaur of the day: Aletopelta

• Ankylosaurid that lived in the Late Cretaceous in what is now California, U.S. (Point Loma Formation)
• Walked on all fours, had a bulky body, low to the ground, covered in armor, had spikes, had a long tail and relatively short neck
• Shoulder spikes are like handles, if you were to ride it
• No skull found
• No club tail found
• But thought to be an ankylosaurid based on its unique armor
• Had thick shoulder scutes and long spikes, and polygonal scutes that covered the pelvis
• Ankylosaurids were covered in armor and had club tails and broader heads than nodosaurids
• Estimated to be about 16 ft (5 m) long and weigh 2 tonnes
• Originally estimated to be almost 20 ft (6 m) long
• According to the San Diego Natural History Museum, or The Nat, this specimen was about 4 ft (1.3 m) tall and about 13 ft (4 m) long
• Type and only species is Aletopelta coombsi
• Fossils found during construction work in 1987. A skeleton found by a ditch that was dug for a sewage pipe
• Found a partial skeleton with osteoderms
• Brad Riney, a paleontologist at the museum, found the dinosaur during a road extension project (saw the dark brown fossils)
• Lots of marine invertebrates in the formation, as well as a femur, right lower jaw with teeth, and neck vertebra of a hadrosaur
• Riney had also found the nearby hadrosaur fossils
• Had a distinct, leaf-shaped tooth, which is how they knew it was part of Ankylosauria
• San Diego Natural History Museum got the specimen, which was called the “Carlsbad Ankylosaur”
• Holotype includes teeth, fragments of the shoulder, part of the arms, part of the pelvis, both legs, four to five partial vertebrae, fragmentary ribs, and osteoderms including the pelvic shield and cervical half ring (on the neck)
• Found eight teeth
• Probably an immature specimen, based on its unfused astragalus, partly fused scutes, and unfused neural spines
• Fossils described in 1996 by Walter Coombs, Jr. and Thomas Deméré but not named. They thought it was an indeterminate nodosaurid with similarities to Edmontonia, Panoplosaurus, and Stegopelta
• Named in 2001 by Tracy Ford and James Kirkland
• When it was named, it was the only formally named dinosaur from California
• Genus name Aletopelta means “wanderer shield”
• Named for its armor and the fact that the dinosaur skeleton had traveled a long way
• At the time, Carlsbad, CA, where Aletopelta was found, was off the coast of the middle of Mexico or just north of the middle of Mexico
• Tectonic plates shifted, and it ended up in California, where it was found
• Species name is in honor of Walter Preston Coombs, Jr.
• Based on its armor, thought to be an ankylosaurid
• Ford and Kirkland further prepared the skeleton and found the unique features
• Originally named based on a number of features, including in the teeth (wider than they were tall), having a long femur (thigh bone) than tibia and fibula, a pelvic shield with polygonal osteoderms, a large short-pointed spike in the shoulder, and other details in the osteoderms
• Said the pelvic armor had superficial similarities to Stegopelta
• Wrote: “The pelvic scutes of Aletopelta are uniform in shape, although of different sizes. The scutes of Stegopelta are more irregularly shaped and are larger in relative size to the ilia than are those of Aletopelta.”
• Later, in 2015, Victoria Arbour and Phil Currie said it was unique in the osteoderms, including having hexagonal pelvic osteoderms, and the cervical half ring being made of osteoderms fused to an underlying bony band
• Some scientists have considered Aletopelta to be a nomen dubium
• Arbour and Currie found it to be valid
• Holotype formed a mini reef
• Probably died inland and then got swept away
• Probably bloated and floated out to the sea via a stream, then sank to the bottom belly up
• Bloated with gas and then swept away in water and eventually decomposes or gets eaten by scavengers, and it sinks to the bottom of the water
• Became a miniature reef. Found with molluscs like oysters and spiny oysters attached to the bones, and ammonites and gastropods near the skeleton
• Made most of the limb bones hollow and there were lots of shallow pits on the osteoderms and ribs
• Found fossilized oysters and a shark tooth with the bones
• Other nodosaurids have been found in marine sediments, and some are known only from marine strata, including Nodosaurus, Stegopelta, Pawpawsaurus, Niobrarasaurus
• First ankylosaurid to be recovered from marine strata
• Site is close to shore and next to rugged terrain, so “finding a taxon more typical of inland environments is not completely unexpected”

Fun Fact:

There are a dozen non-avian dinosaurs that include “tyran” in their name. Tyrannomimus is only the second that wasn’t considered a tyrannosauroid when it was named.

Genera that are probably tyrannosauroids:

1. Aviatyrannis 2003
2. Dinotyrannus* 1995
3. Eotyrannus 2001
4. Juratyrant 2012
5. Nanotyrannus* 1988 (*name no longer used)
6. Siamotyrannus 1996 (less certain)
7. Sinotyrannus 2009
8. Suskityrannus 2019
9. Tyrannosaurus 1905
10. Yutyrannus 2012
11. Zhuchengtyrannus 2011
12. Tyrannotitan 2005 ( Carcharodontosaurid)

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