Episode 456: The oldest diplodocoid and a brand new Egyptian titanosaur

Episode 456: The oldest diplodocoid and a brand new Egyptian titanosaur. Tharosaurus, a dicraeosaurid like Amargasaurus, is the oldest diplodocoid ever discovered; The brand new titanosaur, Igai, was described from Egypt; and we discover how cupboards of curiosity had been the unique pure historical past museums

Information:

• There’s a brand new titanosaur, Igai semkhu supply
• There’s a brand new dicraeosaurid sauropod, Tharosaurus indicus supply
• The Ubirajara fossil was formally returned to Brazil in June supply
• Gavin Leng, a fossil hunter identified for discoveries similar to Eotyrannus, just lately handed away supply
• Should you’re in London, try the Brick Dinos exhibit on the Horniman Museum & Gardens supply

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The dinosaur of the day: Megapnosaurus

• Additionally contains Syntarsus and to some extent Coelophysis
• Talked about Megapnosaurus/Syntarsus briefly in episode 426 (there’s a pair of them on show in a diorama on the Pure Historical past Museum of Zimbabwe)
• Coelophysid theropod that lived within the Early Jurassic in what’s now Africa and probably the U.S.
• Seemed like Coelophysis, had a protracted tail, walked on two legs, had brief arms, and a protracted face
• Related in dimension and form to Coelophysis
• Small to medium sized
• Estimated to develop as much as 7.2 ft (2.2 m) lengthy and weigh as much as 29 lb (13 kg)
• Evenly constructed and quick
• Had a big mind cavity, so most likely clever particularly in comparison with different dinosaurs
• Based mostly on progress rings, lived on common seven years
• Could have been nocturnal, based mostly on scleral rings trying much like fashionable nocturnal birds
• Had a “weak joint” within the jaw bones, which gave it a hooked premaxillary jaw (tip of the snout)
• Speculation then that it was a scavenger (couldn’t go after stay prey)
• Identify continues to be debated, as Megapnosaurus, Coelophysis or a brand new genera
• Genus title Megapnosaurus means “large useless lizard”
• Two species? Megapnosaurus rhodesiensis and Megapnosaurus kayentakatae
• Some paleontologists take into account Megapnosaurus to be synonymous with Coelophysis, however that is nonetheless being debated
• Begin with Megapnosaurus rhodesiensis
• Megapnosaurus rhodesiensis discovered within the Elliot Formation in South Africa and the Forest Sandstone Formation in Rhodesia (now often known as Zimbabwe)
• Megapnosaurus rhodesiensis estimated to be as much as 7.2 ft (2.2 m) lengthy and weigh as much as 29 lb (13 kg)
• Described as lean and lengthy, with an s-shaped neck, lengthy legs that regarded like legs of birds just like the secretary chicken (which seems prefer it’s strolling on stilts)
• Had shorter arms, with 4 fingers on every hand, and a protracted tail
• No proof it had feathers, however usually portrayed that manner, as a result of it regarded so bird-like
• Fossils first present in 1963
• Holotype contains most of a nicely preserved skeleton (solely lacking cranium and neck vertebrae)
• Extra fragments additionally discovered
• A number of specimens present in 1985 in South Africa (Elliot Formation), and 26 specimens collected in Zimbabwe (Forest Sandstone Formation) in 1963, 1968, and 1972
• Elliot Formation most likely an historical flood plain. Different dinosaurs that lived across the identical time and place embrace the sauropodomorphs Massospondylus and Ignavusaurus, additionally ornithischians like Lesothosaurus and Heterodontosaurus
• Forest Sandstone Formation had crocodiles, Massospondylus and indeterminate prosauropods
• In 1972, Raath discovered lots of of bones from at the very least 26 people from completely different progress levels (included skulls and neck vertebrae, in addition to intestine contents)
• Raath described the fossils in his thesis in 1977 (fossils from that locality now on the Queen Victoria Museum in Australia)
• Healed fractures of the leg and toes present in Megapnosaurus rhodesiensis, and one specimen had indicators within the sacral rib of fluctuating asymmetry, which can be from residing in aggravating situations
• Potential they hunted in packs
• Potential sexual dimorphism, based mostly on some people being strong with giant limbs and enormous muscle attachments in comparison with extra gracile people which might be comparable in dimension (and adults)
• A number of variable progress, with some people being bigger however youthful/extra immature than smaller, mature adults
• Variable progress seemingly widespread in earlier dinosaurs however later misplaced (birds don’t do it), and will have helped early dinosaurs adapt to harsh environments
• Initially named Syntarsus rhodesiensis by Michael Raath in 1969 based mostly on the Zimbabwe (Rhodesia) fossils
• However in 2001, discovered there was a beetle named Syntarsus asperulus
• Ivie and others renamed Syntarsus rhodesiensis to Megapnosaurus in 2001
• Some controversy right here (will get into)
• In 2001, Michael Ivie and others named Megapnosaurus and mixed Megapnosaurus rhodesiensis (named by Raath in 1969) and Megapnosaurus kayentakatae (named by Rowe in 1989)
• Syntarsus asperulus was a beetle, named in 1869 by Fairmaire (although two of the authors, together with Ivie made it a junior synonym of Cerchanotus in 1990—however nonetheless, title had been already used)
• Based on Ivie and others: “This flip of occasions requires a brand new title, and though S. rhodesiensis is described inside the quilt of the 1996 quantity 3 of the journal SYTNTARSUS as “a small carnivorous dinosaur,” and though nearly as good and constant phylogeneticists, we perceive that it was probably not on the lizard lineage, on the scale of an entomologist, it seems like a giant useless lizard. So, in what might be the primary title for a dinosaur each proposed in an entomological journal, we suggest the alternative title Megapnosaurus”
• “[…] this moniker appears extremely acceptable for this animal”
• Debates on whether or not to lump Megapnosaurus into Coelophysis (and make Megapnosaurus rhodesiensis a junior synonym, to grow to be Coelophysis rhodesiensis)
• Gregory Paul, Michael Raath, and others agree
• Talked about Coelophysis in episode 204
• A pair research in 2018, by Barta and others and by Christopher Griffin, discovered sufficient variations to maintain them separate
• Some examples: Megapnosaurus rhodesiensis doesn’t have a fifth hand bone (metacarpal) and Coelophysis bauri does
• Additionally variations in scars, grooves, and depressions on the humerus and femur (arm and leg bones)
• Now on to Megapnosaurus kayentakatae
• In 1989, Timothy Rowe described a second species of “Syntarsus”, as Syntarsus kayentakatae, based mostly on a cranium and components of a skeleton
• Fossils discovered within the Kayenta Formation in Arizona, U.S. (Early Jurassic)
• Kayenta Formation had rivers, and wet summers and dry winters
• Different dinosaurs from the Kayenta Formation embrace theropods like Dilophosaurus and Kayentavenator (which was initially considered Syntarsus kayentakatae/Megapnosaurus kayentakatae—however there are sufficient variations to be separate), the “Shake-N-Bake” theropod, an undescribed coelophysoid identified from a partial skeleton present in 1978 (numerous small bones cemented collectively in a dense matrix as a result of the fossils had washed down collectively), sauropodomorphs like Sarahsaurus and Anchisaurus, heterodontosaurs, and armored dinos like Scelidosaurus and Scutellosaurus
• Different animals that lived across the identical time and place embrace sharks, fish, frogs, turtles, lizards, pterosaurs, mammals, crocodylomorphs, mussels, and snails
• Discovered at the very least 16 people of Syntarsus kayentakatae (fragmentary stays)
• Fossils discovered between 1977 and 1979
• Sort specimen of Syntarsus kayentakatae is a totally mature, strong grownup
• Holotype of Syntarsus kayentakatae was distorted (principally left facet preserved, as a result of it rested on left facet and was partially buried, however proper facet together with the cranium was uncovered to water currents)
• Species title refers to Dr. Kathleen Smith, who has the nickname “Kayenta Kay” due to her work within the Kayenta Formation, which incorporates discovering the sort specimen of Megapnosaurus kayentakatae
• Megapnosaurus kayentakatae estimated to be as much as 8.2 ft (2.5 m) lengthy and weigh as much as 66 lb (30 kg)
• One large distinction between Megapnosaurus rhodesiensis and Megapnosaurus kayentakatae is that Megapnosaurus kayentakatae had two small crests on its head (much like Dilophosaurus however smaller)
• Whether or not to make use of the title Megapnosaurus or Syntarsus is dependent upon who you ask
• In 2000, Alex Downs in contrast Coelophysis bauri and Syntarsus rhodesiensis and located them to be so comparable that Syntarsus was a junior synonym to Coelophysis (solely had minor particulars within the neck size and different small variations)
• In 2004 Anthea Bristowe and Michael Raath synonymized Coelophysis and Syntarsus as nicely, based mostly on work on {a partially} disarticulated cranium of a juvenile Syntarsus specimen
• Mentioned “that the just lately proposed facetious alternative title for Syntarsus (Megapnosaurus) mustn’t stand”
• Discovered solely minor variations and mentioned that may very well be as a result of they lived at completely different occasions (Coelophysis in Late Triassic and Syntarsus in Early Jurassic)
• In 2017, Daniel Barta and others discovered variations within the arms of Coelophysis bauri and Megapnosaurus rhodesiensis (fifth metacarpal)
• In 2018 Christopher Griffin discovered Megapnosaurus to be legitimate (sufficient variations between the 2, together with that there have been some characters that various as Megapnosaurus grew that weren’t present in Coelophysis, like scar on the humerus, and depressions on the femur)
• Although, did so a lot of the options that modified whereas rising (throughout ontogeny) had been the identical, they usually had been comparable in dimension as soon as absolutely grown
• In 2020 Adam Marsh and Timothy Rowe saved the title Syntarsus rhodesiensis as an alternative of utilizing Megapnosaurus or Coelophysis “as a result of the systematic relationships of those animals inside Coelophysoidea is in flux”
• In 2021 Ezcurra and others discovered that Syntarsus kayentakatae was not carefully associated to Coelophysis bauri or Megapnosaurus rhodesiensis
• In 2022 Skye McDavid and Jeb Bugos discovered Megapnosaurus rhodesiensis to be the legitimate title
• Controversy on the title change to Megapnosaurus and whether or not the way it was modified was legitimate (some sources mentioned whether or not it was ethically executed)
• Based on McDavid and Bugos, “If a taxonomic title is invalid (preoccupied or incorrectly formulated), then it’s thought of moral to contact its authentic describer or describers to tell them of the issue in order that they’ll right their very own error. If the unique describer or describers are unreachable (for instance if they’re deceased or don’t reply to correspondence) then the one that learns of the error will sometimes publish a correction. Ivie tried to contact Raath however by no means obtained a reply. He and coauthors proceeded with publication of the alternative title after two years, and after being (incorrectly) informed by dinosaur paleontologist John “Jack” Horner that Raath was deceased. (Michael Ivie, pers. comm.)”
• Additionally mentioned, “The genus Megapnosaurus is right here thought of to be seemingly distinct from Coelophysis, however in want of additional analysis”
• Discovered Megapnosaurus rhodesiensis to be right, for now, however mentioned it might probably be a junior synonym and “utilization of the title Megapnosaurus rhodesiensis is really useful. Utilization of the title Coelophysis rhodesiensis is neither really useful nor discouraged. Utilization of the title Syntarsus rhodesiensis is discouraged.”
• Additionally discovered that Syntarsus kayentakatae is most definitely its personal genus, and suggest or not it’s provisionally known as ‘Megapnosaurus’ kayentakatae, “with citation marks indicating a problematic genus task, till a brand new genus is formally described for this species”
• Different fossils discovered that could be Megapnosaurus or was once Megapnosaurus/Syntarsus
• Darlington Munyikwa and Michael Raath described a part of a Megapnosaurus/Syntarsus snout discovered within the Elliot Formation in South Africa (that is now often known as Dracovenator)
• A number of coelophysoid bones present in Mexico from the Early Jurassic had been described as “Syntarsus” “mexicanum” however they weren’t correctly described and are most likely from an indeterminate coelophysoid
• Scientists referred a theropod specimen from Wales to Syntarsus sp. However in 2021 that was later named Pendraig (talked about in ep 360)
• In 2004, Randall Irmis reported fossils of Megapnosaurus present in Lufeng Formation, China, Early Jurassic (two specimens discovered). Would imply Megapnosaurus was additionally in Asia

Enjoyable Reality:

Dicraeosaurids should not distinctive for his or her bifurcated neural spines (like these on Amargasaurus), even we’ve got them!

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