Episode 36 is all about Troodon, one of many smartest dinosaurs, and in addition a theropod, initially named primarily based on simply on tooth.
You may hearken to our free podcast, with all our episodes, on iTunes at:
https://itunes.apple.com/us/podcast/i-know-dino/id960976813?mt=2
On this episode, we focus on:
- The dinosaur of the day: Troodon formosus, whose identify means “wounding tooth”
- Lived within the Cretaceous
- Fossils present in Alaska, Wyoming, presumably Texas and New Mexico
- Found in 1855, one of many first dinosaurs present in North America
- Troodon fossil present in 1855 by Ferdinand V. Hayden, however named by Joseph Leidy in 1856
- Initially spelled Troödon (named by Joseph Leidy in 1856, however modified by Sauvage in 1876
- Kind specimen was primarily based on one tooth present in Judith River Formation, which induced some classification issues
- Initially Troodon tooth classifed as a lizard, then grew to become a megalosaurid (1901–wastbasket taxon), then Gilmore urged in 1924 that it was a Stegoceras (pachycephalosaur), and the household Pachycephalosauridae was referred to as Troodontidae for some time. However in 1945, Charles Mortram Sternberg mentioned Troodon’s enamel was too just like carnivore dinosaurs, and reclassified it as a theropod (making Troodontidae irrelevant, so the household was renamed Pachycephalosauridae)
- In 1932, Sternberg discovered a foot, components of hand, and tail vertebrae within the Dinosaur Park Formation in Alberta. Named it Stenonychosaurus, however in 1951 determined it was carefully associated to Troodon, although no different specimens had been found but to check his principle
- Dale Russell discovered a extra full Stenonychosaurus in 1969 (additionally from Dinosaur Park Formation), and it was well-known theropod within the Nineteen Eighties. It was categorized as a part of the household Saurornithoididae, together with Saurornithoides, which have been thought of to be shut family members of Troodon. In 1987 Phil Currie analyzed the specimens and located that the totally different tooth and jaw constructions of troodontids and saurornithoidids have been due to age, not distinction in species. He reclassified Stenonychosaurus inequalis as a junior of Troodon formosus (together with Polydontosaurus grandis and Pectinodon bakkeri). In 1988 Gregory S. Paul additionally categorized Saurornithoides mongoliensis as Troodon mongoliensis, however not all scientists accepted it.
- However Currie and different paleontologists then questioned whether or not all of the specimens have been one Troodon species and famous in 1990 that although the specimens from Judith River have been Troodon formosus, different troodontids from Hell Creek Formation and Lance Formation could also be totally different species. George Olshevsky mentioned in 1991 that the Lance formation fossils have been Troodon bakkeri (previously Pectinodon bakkeri, then Troodon formosus), and different scientists name the Dinosaur Park Formation fossils Troodon inequalis (previously Stenonychosaurus inequalis)
- Zanno and a workforce reviewed troodontids in 2011 and located that Pectinodon bakkeri was a legitimate genus and lots of the Troodon formosus specimens may very well be a couple of species, however would require additional research (the holotype Troodon is only one tooth, so Troodon could also be a nomen dubium)
- Troodon species come from totally different areas and several other million years aside
- Solely approach to correctly determine it out is to have a neotype specimen (and never only a tooth) to match all of the specimens to and decide if there are a number of species of Troodon
- A neotype specimen “units the usual for the species”
- Dale A. Russell, who discovered the primary Troodon cranium, urged in 1982 that had Troodon not gone extinct, it could have advanced to have a mind case just like a people (since its EQ was 6x larger than different dinosaurs)
- Russell known as it a “Dinosauroid” and mentioned Troodontids would have had giant eyes, three fingers on every hand, toothless beaks, and fed younger like birds with regurgiated meals (and language would sound like hen music)
- Many paleontologists have criticized the Dinosaurid as too anthropomorphic
- Small, 3 toes tall (0.9 m), 7.9 ft lengthy (2.4 m), 110 lbs (50 kg)
- Reached grownup dimension at 3-5 years
- Largest Troodon are related in dimension to Deinonychus
- Intently associated to dromaeosaurids (these theropod teams are the closest family members to birds)
- Bipedal, stiff tail
- Lengthy hind limbs, so in all probability may run rapidly; additionally retractable sickle claw on second toes (didn’t contact the bottom when working)
- Might have had primitive feathers (may have insulated in Alaska)
- Troodon in all probability most well-liked cooler climates
- Lived close to streams and deltas of coastal plains on Larimidia, together with Euoplocephalus, Dromaeosaurus and Nanuqsaurus
- Very giant mind relative to physique mass (just like fashionable birds)
- Scientists who reconstructed a Troodon’s mind discovered it could have begun to fold onto itself (totally different from different reconstructed dinosaur brains); the folded, wrinkled look is seen in people and animals with a lot of mind energy
- Exhausting to know its precise intelligence, although scientists suppose it was at the very least as sensible as a contemporary opossum
- Undecided if it was omnivore or carnivore
- Might have been an omnivore (serrations are considerably just like herbivorous reptiles)
- Troodon jaws meet in a broad U-shape, just like an iguana (which eats vegetation), and enamel have giant serrations (known as denticles) like plant eaters; nevertheless it had greedy palms, was sensible (just like raccoons, for instance, omnivores)
- Troodon had an opposable finger; unsure the way it used it, however may have helped seek for prey in branches or on the bottom
- However may have been a predator (sickle claw and binocular imaginative and prescient)
- Troodon had recurved enamel (curved in direction of the tip factors to the again of the mouth to assist seize prey)
- T-rex additionally had a U-shaped snout so it may take bigger bites of prey
- Good sense of listening to
- Higher sense of scent than fashionable birds, however inferior to crocodiles and enormous theropods like T-rex
- Massive eyes, so might have been nocturnal, and confronted barely ahead, so had some depth notion
- Massive eyes helped it hunt at evening or throughout lengthy winters
- Troodon in Alaska (because of the darkish and having giant eyes to see in the dead of night) might have advanced to be greater to assist fill the hole left by the bigger carnivores (didn’t stay there)
- One research of Troodon enamel present in northern websites (Alaska), bigger than enamel from southern websites, suggesting northern Troodon grew bigger and will have been in a position to hunt bigger animals; additionally discovered that put on patterns in enamel confirmed it ate delicate meals (not robust vegetation, however meat)
- One Troodon bone might have had a chunk wound
- Some have speculated Troodon might have hunted in packs (no actual proof)
- Might have eaten a mixture of small lizards, malls, invertebrates, and plant materials
- Jack Horner discovered the nests in Two Medication Formation in Montana in 1983 together with David Varrichio
- Varricchio and workforce described in 1997 Troodon nests (dish formed, about 100 cm in diameter, with a rim encircling the eggs. Full nests had between 16 and 24 eggs, which have been formed like lengthy teardrops
- Varricchio and workforce discovered that (primarily based on nests), Troodon reproduced in a method in between crocodiles and birds; eggs grouped as pairs (so had two practical ovaries like crocodiles–birds solely have one to assist them fly) and Troodon laid eggs about 0.5 kg for a 50 kg grownup (10 occasions bigger than reptiles the identical mass, however just like what birds do)
- Varricchio and workforce discovered proof of iterative laying (lays a pair of eggs daily or two, then delays brooding till completed laying eggs); embryos all in similar phases of improvement, so in all probability hatched across the similar time; might take 45-65 days for laying, brooding and hatching; no proof they stayed in nest (might have left, like crocodiles)
- The location had a male grownup Troodon
- Workforce additionally discovered that male Troodons in all probability brooded, and never females, primarily based on bone histology of a Troodon specimen that didn’t have “bone resorption patterns that might point out it was an egg-laying feminine”
- Troodon eggs laid vertically, and would have buried bottoms of the egg in mud (extra just like birds than crocodiles, which fully bury eggs)
- Just like Egyptian Plover hen that broods eggs which are partially buried in sand
- The workforce studied the eggs and in contrast them to the variety of pores in hen and crocodile eggshells (crocodile eggs have extra pores for respiration, since they’re buried). Might assist to determine how future dinosaur eggs discovered have been incubated
- Troodontidae is a small group of maniraptorans
- Small and really bird-like (one Troodontid, known as Sinovenator, is similar to Archaeopteryx
- Some scientists have urged Troodontidae have been ancestors of birds, however most imagine it was dromaeosaurs
- Troodontid genuses embody Saurornithoides (Mongolia), Troodon (North America), and Sinornithoids
- Different troodontids embody Borogovia (named after Lewis Carroll poem) and Zanabazar (named after Mongolian religious determine), and Mei
- They’ve a lot of enamel and carefully spaced enamel in decrease jaw
- Lengthy legs, giant curved claw on second toes that retracts when it runs (just like dromaeosaurids, however smaller)
- Troodontids have sickle-claws and excessive EQs (very sensible)
- Good listening to
- Ears have been asymmetrical (one larger than the opposite, just like owls), so might have hunted like owls, utilizing listening to to find prey
- Some might have been omnivorous although most have been in all probability carnivorous
- Some troodont fossils present they roosted like birds (Mei), and helps principle that they in all probability had feathers
- Chinese language Mei lengthy (soundly sleeping dragon) is a specimen with legs folded and nostril tucked beneath one wing-like arm, seems to be prefer it’s sleeping (a troodontid)
- Primitive troodontids like Jinfengopteryx and Anchiornis have been discovered totally feathered
- Largest Troodontid is Troodon and smallest is Anchiornis
- In 2004 Mark Norell and workforce discovered two partial troodontid skulls in an oviraptorid nest; unsure why they have been there (nest parasites or prey for the oviraptorids or its hatchlings)
- Enjoyable truth: Birds and reptiles that stay as we speak have one opening of their physique for urinating, defecating, and reproducing. It’s known as a cloaca, which in Latin means “sewer”, and scientists imagine dinosaurs additionally had a cloaca.