Episode 549: The Best Discovery of the Year!. A new Spicomellus find reveals just how crazy its armor was. Plus Six brand new sauropods!

News:

• A much more complete Spicomellus skeleton was found with some of the strangest and most elaborate armor ever seen source
• There’s a new sauropodomorph species, Xingxiulong yueorum, which is quite a bit bigger than the previous species from the genus source
• The oldest known sauropodomorph from East Asia, Wudingloong wui, was just described source
• There’s a new eusauropod, Huashanosaurus qini, named for famous mountain with impressive rock art source
• There’s a new mamenchisaurid sauropod, Tongnanlong zhimingi, which is estimated to be over 80ft long source
• There’s a new rebbachisaurid (vacuum cleaner head) sauropod, Cienciargentina sanchezi, from Patagonia source
• There’s another new rebbachisaurid, Astigmasaura genuflexa, measuring in at about 59ft (18m) long and weighing over 10 tons source

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The dinosaur of the day: Liaoningosaurus

• Ankylosaur that lived in the Early Cretaceous in what is now Liaoning Province, China (Yixian and Jiufotang Formations)
• Looked like a tiny Ankylosaurus but without the club on the tail
• Walked on four legs, had a long tail, and a small head
• Oldest known ankylosaurid to have a tail club
• Had a tail club handle but didn’t seem to have a tail club knob
• Had short hands
• Feet were longer than the hands
• Had a mix of nodosaur and ankylosaur features
• Named in 2001 by Xing Xu, Xiao-Lin Wang, and Hai-Lu You
• Type and only species is Liaoningosaurus paradoxus
• Genus name means “Liaoning lizard”
• Species name refers to the “surprising characteristics of this animal”
• The type specimen is a nearly complete, articulated skeleton that is a little over 1 ft (34 cm) long (a juvenile)
• A nearly complete skeleton was later described that was larger and filled in some gaps (had five digits on each hand, upper arm bone or humerus almost as long as the femur or tibia, leg bones)
• More specimens have been found and referred to Liaoningosaurus since
• Type specimen had very few spikes or armor on its back (possibly because it was a juvenile, not fully grown)
• Also thought to have two large bone plates covering the belly (there is some debate on this)
• Has been described as having a “shell-like” bony plate covering the underside of its torso
• One paper said there are a few hundred specimens of Liaoningosaurus
• Only two specimens have been officially described
• The second specimen, described in 2016, led to the hypothesis that Liaoningosaurus may have been semiaquatic, for a few reasons:
• Ji and others in 2016 suggested that the underbelly armor helped protect it from underwater attacks, and said the lack of fusion between the spine and hip bones helped it in the water (though others argued it was a feature of being a juvenile, and that’s why there is a lack of fusion in some of the bones)
• But in 2014 Arbour and others suggested that structure was just skin impressions in the type specimen
• A 2018 study suggested the structure may have been formed by a shield around the hips and had a scale cover
• The 2016 paper also suggested Liaoningosaurus may have been semiaquatic because the second specimen was found in an aquatic setting
• However, just because a fossil was found in an aquatic setting doesn’t necessarily mean the animal was aquatic
• The 2016 paper also suggested Liaoningosaurus was a carnivore, based on the long, fork-like denticles of the crowns of the cheek teeth, the sharp claws on the hands and feet, and the fact that parts of fish skeletons were found preserved in the ribcage, as well as a lizard tail (lizard tail may be evidence of scavenging)
• Ankylosaur teeth tend to be triangular or leaf-shaped with lots of denticles (points)
• The teeth of Liaoningosaurus were similar, but the gaps between the denticles go almost to the base of the tooth, so the tooth looks like a comb (maybe more carnivorous)
• Not everyone agrees
• Hard to prove gut contents
• Seems to be no other evidence of gut contents in other specimens (though they haven’t been formally described)
• Several possibilities as to how the fish ended up in the ribcage
• 1) Fish may have been swept into the body. They were at the bottom of the lake and underwater turbulence moved them to the ribcage, though the authors argued this wasn’t likely because the fish weren’t found outside the body
• 2) Fish may have died in the ribcage while scavenging the dinosaur or they sheltered inside the dinosaur and died there, though the authors argued this wasn’t likely because there were no openings in the body or signs of scavenging, such as broken ribs (however, as some people have pointed out, no soft tissue impressions either, which makes it harder to know for sure. Other arguments against include the way the fish were scattered seems to show the fish were scavenging)
• 3) The fish were eaten by the dinosaur. The authors thought this the most likely because it was partial fish remains, possibly from digestive acids, and fish skeletons were found on both sides of the body, not tightly packed in the stomach area, which could mean they got expelled from gas after the dinosaur died. Also the lizard (couldn’t find much on the lizard tail)
• Hope in the future more studies done on the hundreds of other specimens. Could tell us a lot
• Lived in a freshwater environment with lakes, in a place with wet and dry seasons
• Other dinosaurs that lived around the same time and place include birds, as well as hardosauroids like Bolong, the ceratopsian Psittacosaurus, the neornithischian Jeholosaurus, sauropods including Dongbeititan, dromaeosaurs including Sinornithosaurus and Microraptor, troodontids Mei and Sinovenator, the therizinosaur Beipiaosaurus, oviraptorosaurs like Caudipteryx and Similicaudipteryx, ornithomimosaurs like Hexing, the compsognathid Sinosauropteryx, and tyrannosaurs like Dilong, Yutyrannus, and Sinotyrannus
• Other animals that lived around the same time and place include insects, amphibians, pterosaurs, and mammals

Fun Fact:

The stegosaur Miragaia had a muscular tail and intimidating spikes.

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