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Tyrannosaurus rex
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Yes but...
Mammals, only, are able to be pregnant animals, never the birds. Birds can be only gravid... Not the same thing. If we have to find out similarities between dinosaurs and birds, this discovery is too enormous (to be true). This account skips a step !
http://www.cbc.ca/news/canada/toronto/di...-1.3588975
One of the world's most famous predators, the fearsome Tyrannosaurus rex is typically shown baring dozens of sharp, jagged teeth — but a Toronto researcher says the carnivore likely had lips to cover them. Robert Reisz, a professor at the University of Toronto who specializes in vertebrate paleontology, says that contrary to what's shown in movies and even museums, T. rex and his fellow theropods would not have teeth that stick out even when their mouths are closed. His research is set to be presented Friday at a conference of the Canadian Society of Vertebrate Paleontology conference, held at the university's Mississauga campus. The two-day conference begins Thursday. Reisz says only a few land animals, such as elephants and wild boars, have exposed teeth and these have no enamel. Meanwhile, the only animal with bared teeth that have enamel is the crocodile, which is aquatic.  (05-20-2016, 02:26 PM)brotherbear Wrote: http://www.cbc.ca/news/canada/toronto/di...-1.3588975 Interesting Bro bear. Those had to be some seriously big lips to cover those chompers!
Did the mighty Tyrannosaurus rex sport feathers?
 *This image is copyright of its original author
To sum up quickly in a diagram (being a little bit lazy I prefer the first version...):
 *This image is copyright of its original author
I have for years now had the idea that perhaps T-rex had downy feathers as a dino-chick but then became completely featherless as an adult. Perhaps some day there might be discovered some clues. There may be some truth to post #3 also.
@
Frankly, it's hard to imagine the mega predator's body completely covered by feathers. As concerns some small dinosaurs like coelurosaurids, no problem, but for a big 6-8 tons predator, difficult ! Your hypothesis is perhaps a very good one. 
Secrets behind T. rex's bone crushing bites: T. rex could crush with 8,000 pound bite forces
Date: May 17, 2017 Source: Florida State University Summary: The giant Tyrannosaurus rex pulverized bones by biting down with forces equaling the weight of three small cars while simultaneously generating world record tooth pressures, according to a new study. The giant Tyrannosaurus rex pulverized bones by biting down with forces equaling the weight of three small cars while simultaneously generating world record tooth pressures, according to a new study by a Florida State University-Oklahoma State University research team. In a study published today in Scientific Reports, Florida State University Professor of Biological Science Gregory Erickson and Paul Gignac, assistant professor of Anatomy and Vertebrate Paleontology at Oklahoma State University Center for Health Sciences, explain how T. rex could pulverize bones -- a capacity known as extreme osteophagy that is typically seen in living carnivorous mammals such as wolves and hyenas, but not reptiles whose teeth do not allow for chewing up bones. Erickson and Gignac found that this prehistoric reptile could chow down with nearly 8,000 pounds of force, which is more than two times greater than the bite force of the largest living crocodiles -- today's bite force champions. At the same time, their long, conical teeth generated an astounding 431,000 pounds per square inch of bone-failing tooth pressures. This allowed T. rex to drive open cracks in bone during repetitive, mammal-like biting and produce high-pressure fracture arcades, leading to a catastrophic explosion of some bones. "It was this bone-crunching acumen that helped T. rex to more fully exploit the carcasses of large horned-dinosaurs and duck-billed hadrosaurids whose bones, rich in mineral salts and marrow, were unavailable to smaller, less equipped carnivorous dinosaurs," Gignac said. The researchers built on their extensive experience testing and modeling how the musculature of living crocodilians, which are close relatives of dinosaurs, contribute to bite forces. They then compared the results with birds, which are modern-day dinosaurs, and generated a model for T. rex. From their work on crocodilians, they realized that high bite forces were only part of the story. To understand how the giant dinosaur consumed bone, Erickson and Gignac also needed to understand how those forces were transmitted through the teeth, a measurement they call tooth pressure. "Having high bite force doesn't necessarily mean an animal can puncture hide or pulverize bone, tooth pressure is the biomechanically more relevant parameter," Erickson said. "It is like assuming a 600 horsepower engine guarantees speed. In a Ferrari, sure, but not for a dump truck." In current day, well-known bone crunchers like spotted hyenas and gray wolves have occluding teeth that are used to finely fragment long bones for access to the marrow inside -- a hallmark feature of mammalian osteophagy. Tyrannosaurus rex appears to be unique among reptiles for achieving this mammal-like ability but without specialized, occluding dentition. The new study is one of several by the authors and their colleagues that now show how sophisticated feeding abilities, most like those of modern mammals and their immediate ancestors, actually first appeared in reptiles during the Age of the Dinosaurs. Journal Reference: Paul M. Gignac, Gregory M. Erickson. The Biomechanics Behind Extreme Osteophagy in Tyrannosaurus rex. Scientific Reports, 2017; 7 (1) DOI: 10.1038/s41598-017-02161-w
Investigating the running abilities of Tyrannosaurus rex using stress-constrained multibody dynamic analysis Sellers et al., 2017
Abstract: "The running ability of Tyrannosaurus rex has been intensively studied due to its relevance to interpretations of feeding behaviour and the biomechanics of scaling in giant predatory dinosaurs. Different studies using differing methodologies have produced a very wide range of top speed estimates and there is therefore a need to develop techniques that can improve these predictions. Here we present a new approach that combines two separate biomechanical techniques (multibody dynamic analysis and skeletal stress analysis) to demonstrate that true running gaits would probably lead to unacceptably high skeletal loads in T. rex. Combining these two approaches reduces the high-level of uncertainty in previous predictions associated with unknown soft tissue parameters in dinosaurs, and demonstrates that the relatively long limb segments of T. rex—long argued to indicate competent running ability—would actually have mechanically limited this species to walking gaits. Being limited to walking speeds contradicts arguments of high-speed pursuit predation for the largest bipedal dinosaurs like T. rex, and demonstrates the power of multiphysics approaches for locomotor reconstructions of extinct animals." Other articles related: Tyrannosaurus rex couldn't run, says new research
@Ngala :
About #11: very interesting account but frustrating... If the tyrex couldn't run, what about the other big theropods like Giganotosaurus, carcharodontosaurus, spinosaurus and so on ? Were they unable too to run ? Who were therefore the top predators ? Because if they were unable to run, they only scavenged... Logical. Unless they were aktiv predators when they were joung and by growing up lost their capacities of being aktiv predators... Mercyless period for the fully adult predators ! I can't believe and subscribe to this view.
I partially agree with Jack Horner in that T-rex was the ultimate scavenger of his place and time. A kleptoparasite, much like ( IMO ) Arctodus simus. Not that he wouldn't kill something if the opportunity arose.
 (09-13-2018, 12:12 AM)Spalea Wrote: Very happy to read such conclusions like these ones about the T.rex ! After having read the Jack Horner's book "The complete T.rex" I remember to have been in total disagreement with his theory i.e. the T. rex was a total scavenger. I prefered the Robert T. Bakker's depictions which were revolutionary. Yes, T.rex was probably the most powerfull carnivore that ever existed, no animal had such a perfect design for predation, is a machine designed to kill whatever existed. The only backdown are the arms, but all the other parts of the body, brain and senses, tail, legs and specially the jaguar-like head are designed for predation. Dr Robert Bakker is one of the BEST paleontologist ever! Of course that I support his view about the T. rex!  Jack Horner, sadly, is just a bad joke now, specially with his "idea" of Triceratops=Torosaurus, that was the last nail in his coffin, it is just stupid! He was good, I don't know what happen to him.  About Spinosaurus, yes, I doubth that it will be able to dive, but it can surelly swim, and with that size, that was more than enoght to catch its giant prey. Oh yes, there were fishes as large as rhinos in his habitat!!!
Very happy to read such conclusions like these ones about the T.rex ! After having read the Jack Horner's book "The complete T.rex" I remember to have been in total disagreement with his theory i.e. the T. rex was a total scavenger. I prefered the Robert T. Bakker's depictions which were revolutionary.
I read that book, "The Complete T-rex". I bought it on my one-trip to Washington D.C. I believe that T-rex did a lot of scavenging and displacing raptors from their kills. But no big carnivore that I ever heard of is 100% scavenger. I believe that T-rex could kill pretty much anything that he could catch but I doubt anything his size could run anything but a very short spurt. Sorry to continue this off topic. |
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