Episode 448: The Dinosauroid (the human-troodontid hybrid)

Episode 448: The Dinosauroid (the human-troodontid hybrid). Troodon was a brooder, a neuroscientist’s tackle if dinosaurs might turn into as sensible as people, and dinosaur extinction arguments

Information:

• A neuroscientist’s tackle whether or not dinosaurs might evolve to be as clever as people supply
• The talk on what made the dinosaurs go extinct continues, with extra arguments in favor of the Chicxulub influence supply
• Troodon might change its physique temperature and certain brooded its eggs in nests shared with different females of the identical species supply

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The dinosaur of the day: Stenonychosaurus

• Troodontid theropod that lived within the Late Cretaceous in what’s now Alberta, Canada (Dinosaur Park Formation)
• Presumably additionally discovered within the Two Medication Formation
• Seemed like different small theropods, with an extended tail, in all probability coated in feathers, an s-curved neck, quick arms, lengthy legs, and as a troodontid, had sickle-shaped claws on the second toes of every foot
• Estimated to be about 8.2 ft (2.5 m) lengthy and weigh 77 lb (35 kg)
• Had lengthy, slender legs, so could have been a quick runner
• Tail was versatile on the base, which can have helped it flip whereas strolling or operating
• Had giant eyes and binocular imaginative and prescient
• Capable of grasp and maintain objects
• Presumably reached grownup dimension at three to 5 years outdated, based mostly on a troodontid present in Two Medication Formation
• Presumably was an omnivore
• Enamel had been completely different in comparison with different theropods
• Had jaws just like an iguana’s (which eats crops), and the enamel had giant serrations
• In 1988 Tom Holtz and Daniel Brinkman discovered that troodontid enamel had bigger denticles than different theropods, and that the serration scaling is what made it so complicated on how one can classify Troodon when it was first described
• Stenonychosaurus and Troodon have been lumped and break up prior to now, and Troodon was named from a single tooth, in 1856 (a part of why it’s complicated)
• Talked about Troodon in episode 36
• Steered Troodon would have additionally eaten eggs and invertebrates (like worms), and others have instructed troodontids ate bugs
• Sort and solely species is Stenonychosaurus inequalis
• Genus identify means “slender claw lizard”
• Named by Charles M. Sternberg in 1932
• Sternberg described a left foot, components of a hand, and a few tail vertebrae
• In 1932, Sternberg wrote: “Observant collectors and college students of vertebrate paleontology, who’ve studied the Stomach River and Edmonton faunas totally notice that, despite the various effective dinosaurian specimens which have been collected from these beds lately, many kinds are nonetheless imperfectly recognized. Maybe the light-limbed theropods are among the many least recognized of those dinosaurs”
• Sternberg discovered Stenonychosaurus to carefully resemble Ornitholestes, however Stenonychosaurus was greater and had some variations within the tail and toes
• Additionally wrote: “The construction of each the entrance and hind toes of Stenonychosaurus appears to counsel that it must be considered a direct descendant of Ornitholestes although the distinction within the caudal vertebrae is likely to be towards this suggestion” (ended with want to search out extra full specimens/extra fossils to be taught extra)
• Over time, Stenonychosaurus has been reassigned and reclassified
• Russell had at one level synonymized Polyodontosaurus and Ornithomimus altus as Stenonychosaurus however stated there wasn’t sufficient proof to synonymize with Troodon
• Carpenter later synonymized Polyodontosaurus, Stenonychosaurus, Ornithomimus altus, and Troodon formosus as Saurornithoides inequalis
• Currie synonymized Stenonychosaurus and Pectinodon below Troodon formosus
• Phil Currie discovered that variations within the enamel and jaws of troodontids had been based mostly on age and place of the tooth within the jaw, as an alternative of being a function of various species. He reclassified Stenonychosaurus as Troodon, and reclassified different troodontids as Troodon formosus
• Later, different scientists, together with Currie, thought there could also be extra troodontid species. Ended up splitting out Dinosaur Park Formation fossils that was Stenonychosaurus as Troodon inequalis
• In 2011, Lindsay Zanno and others analyzed how troodontids had been categorized, and located all of the specimens assigned to Troodon formosus had been in all probability completely different species, and for the reason that holotype of Troodon is a tooth, Troodon could also be a nomen dubium
• In 2017, Evans and others agreed that the holotype of Troodon was not distinctive sufficient and instructed reviving Stenonychosaurus for troodontid fossils present in Dinosaur Park Formation
• In 2017, Aaron van der Reest and Phil Currie discovered Troodon formosus to now not be legitimate
• Studied a troodontid pelvis van der Reest had present in 2014 in Dinosaur Provincial Park, which led him to analyzing troodontid cranium fossils
• Led to him and Phil Currie resurrecting Stenonychosaurus inequalis and naming Latenivenatrix mcmasterae
• They reassigned a variety of the Stenonychosaurus fossils to a brand new dinosaur, Latenivenatrix
• Coated in episode 144
• Talked about the way it appeared unlikely for all these fossils to belong to Troodon, as a result of that may imply it spanned 15 million years and has been present in what’s now Mexico all the way in which as much as Alaska
• A 2021 research by Thomas Cullen and others discovered that Latenivenatrix was really a junior synonym to Stenonychosaurus (the variations in options had been because of particular person variation)
• In 1969 Dale Russell described a extra full Stenonychosaurus skeleton. This skeleton was the idea for a life-sized sculpture of Stenonychosaurus, and a sculpture of the well-known “dinosauroid”
• In 1982, Russell & Séguin did a thought experiment on what Stenonychosaurus would appear to be if it had continued evolving till at this time
• In 1982, Russell and Séguin wrote: “Stenonychosaurus was a extremely progressive animal for its day”
• Stated: “It may additionally be entertaining to take a position in a qualitative method on how the descendants of S. inequalis might need appeared had they survived the terminal Mesozoic extinctions” and advanced to have an EQ just like people
• Stated that over time, the EQ (encephalization quotient), relative mind weight in comparison with physique weight, in dinosaurs elevated
• Discovered that whereas a Troodontid cranium had a low EQ in comparison with a human, it was rather a lot increased in comparison with different dinosaurs
• Had a big mind, particularly in comparison with different dinosaurs
• Steered that if Stenonychosaurus advanced till at this time, might have an EQ just like a human’s
• Thought the big mind would result in a shorter face, and would ultimately be toothless and have a brief neck to help the bigger mind, and ultimately stroll like a human, and have {a partially} opposed finger on every hand (because it might grasp)
• Being upright would additionally imply no extra tail, or a stump of a tail
• This Dinosauroid regarded very human like
• May additionally argue it regarded like a sci-fi alien, with giant eyes
• Russell and Séguin argued that people have one of the best physique form for our massive brains, which is why Stenonychosaurus would doubtlessly evolve to look extra human, but additionally allowed that they might be biased
• Imagined this Dinosauroid would give stay delivery as an alternative of lay eggs (for the mind energy/bigger brains and heads) and feed regurgitated meals
• Ended the paper with: “The presence of this physique type in Homo sapiens demonstrates that the answer exists. It could, nonetheless, not be distinctive. We invite our colleagues to establish alternate options”
• Thought experiment has had numerous criticism, for the Dinosauroid being too human-like (some scientists have stated it might preserve its theropod physique, and be extra horizontal than vertical, with an extended tail)
• Doable that eggs and nests present in Two Medication Formation in Montana belong to Stenonychosaurus (has been regarded as Orodromeus, then later Troodon, then Van der Reest and Currie stated it was presumably Stenonychosaurus)
• Lived on a heat coastal floodplain coated by forests
• Different dinosaurs that lived across the similar time and place embody Daspletosaurus, Gorgosaurus, Lambeosaurus, Corythosaurus, Prosaurolophus, Styracosaurus, Centrosaurus, Chasmosaurus, Scolosaurus, Euoplocephalus, Edmontonia, Stegoceras, and Foraminacephale

Enjoyable Truth:

Most dinosaurs by no means acquired the prospect to see a butterfly, however some did!

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