Getting Prehistoric with Dinosaurs

6/23/20

https://zoom.us/j/95352293649?pwd=dldnRnNRK2d1M2h3NFRHRzBtc3U1Zz09#success

Introduction:

What are your hobbies/interests? Favorite Dino.?

What are your goals? short-term goals vs long term goals?

Today's activities:

The beginning of the end: What happened 65 million years ago?

T-rex info.

https://www.thoughtco.com/main-dinosaur-types-1091963

Easily the most famous dinosaur that ever lived, Tyrannosaurus Rex is a case study in how much we know, and how much we don’t know, about how dinosaurs behaved millions of years ago. For example, while we have a pretty good idea what T. Rex looked like, we’re still not sure whether it actively hunted its food, whether it was warm- or cold-blooded (or something in between), or even whether it could run faster than a little old lady on a three-speed bike.

Tyrannosaurus Rex: The Early Years Some of the first, fragmentary fossils of Tyrannosaurus Rex were discovered by the famous paleontologist Edward Drinker Cope (with Othniel. C. Marsh, one of the participants in the notorious 19th-century Bone Wars) in South Dakota in 1892. Drinker promptly named his find Manospondylus gigax, which translates roughly as “giant thin vertebra”—and who knows how history might have changed if that colorless name had stuck. (In retrospect, because they were only classified years after the event, various T. Rex fragments were discovered before 1892: scattered teeth in Colorado, in 1874, and skull fragments in Wyoming around 1890.)

Fortunately, a succession of more complete fossil discoveries in Wyoming shortly after the turn of the century (by Barnum Brown, the assistant curator of the American Museum of Natural History who was named after the circus impresario P.T. Barnum) spared the king of dinosaurs from being saddled with the plebeian name Manospondylus. In 1905, the patrician president of Brown's museum, Henry Fairfield Osborn, officially dubbed this dinosaur Tyrannosaurus Rex, Greek for “tyrant lizard king.”

The Tyrannosaur Family Grows Technically, Tyrannosaurus Rex is a species (and the only known species) of the genus Tyrannosaurus. However, paleontologists have since discovered the fossils of numerous related genera, from various parts of the world, which all fall under the general category of tyrannosaurs. Additional tyrannosaur discoveries from North America--including Gorgosaurus, Albertosaurus and Appalachiosaurus--proved different enough from T. Rex to merit being assigned to their own genera, and tyrannosaurs have since been discovered across the expanse of Eurasia, including a few extremely tiny, primitive members of the breed (such as Dilong) from China.

A brief word about another genus that's often included in this list of tyrannosaurs, Nanotyrannus (literally, “tiny tyrant.”) It’s still a matter of some dispute whether this dinosaur, which was identified on the basis of a single fossilized skull discovered in the 1940’s, represents a genuinely new, pint-sized species of tyrannosaur or was simply an unfortunate T. Rex juvenile who happened to die young. It's also possible that Nanotyrannus wasn't a true tyrannosaur at all, but a modestly proportioned theropod of the raptor family.

A Girl (or Boy) Tyrannosaurus Rex Named Sue The most spectacular Tyrannosaurus Rex discovery to date was made by the (then) amateur fossil hunter Sue Hendrickson, who unearthed a near-complete Tyrannosaurus Rex skeleton in South Dakota in 1990. Named “Sue” in Hendrickson’s honor, this individual apparently perished at the age of around 30 from a bite to the head (which counts as natural causes during the Cretaceous period), making it the oldest T. Rex yet identified. (By the way, don’t let the name fool you—it’s unknown whether Dinosaur Sue was male or female, though paleontologists now believe that female tyrannosaurs tended to be bigger than males.)

Proving that no good T. Rex deed goes unpunished, Hendrickson spent the next few years after her discovery immersed in legal proceedings pertaining to Sue’s provenance and ownership--kind of like the custody battle in Kramer vs. Kramer, but with a very, very big child at stake. A court finally ruled that Sue’s bones belonged to the person who owned the piece of land where she was discovered, and in 1997 the remains were auctioned off to Chicago’s Field Museum of Natural History for $8 million, at the time a record amount of cash for a single dinosaur.

So Many Tyrannosaurus Rex Questions… In a way, the popularity of Tyrannosaurus Rex has been both a blessing and a curse for paleontologists. On the plus side, any scientist who makes a major discovery about T. Rex behavior or physiology is sure to land herself front-page headlines around the world. On the minus side, people don’t like it when their idols are tampered with, especially if a supposedly fearsome, unstoppable dinosaur is shown to be, well, kind of a wimp, or even (heavens forfend) covered with feathers. (There is now some indirect evidence, extrapolated from feathered tyrannosaurs like Yutyrannus, that T. Rex was feathered during at least some part of its life cycle, possibly when it was a hatchling or juvenile.)

For example, nothing gets a Tyrannosaurus Rex fan’s blood boiling like the theory that T. Rex scavenged for its food rather than actively hunting it down (the evidence today points to this dinosaur indulging in both behaviors, making Rex an opportunistic predator; see Was T. Rex a

Hunter or Scavenger?)), or that this dinosaur was slower than a New York City bus during rush hour, rather than the speedy menace of the Jurassic Park movies (see How Fast Could Dinosaurs Run?). No matter what the experts say, though, you can be sure that Hollywood will go on portraying Tyrannosaurus Rex the old-fashioned way--as the perpetually grumpy, hungry, fleet-footed king of the dinosaurs.

Tyrannosaurus rex is by far the most popular dinosaur, having spawned a huge number of books, movies, TV shows, and video games. What's truly amazing, though, is how much what was once assumed as fact about this carnivore has later been called into question and how much is still being discovered.

Tyrannosaurs were the killing machines of the late Cretaceous period. These huge, powerful carnivores were all legs, trunk, and teeth, and they preyed relentlessly on smaller, herbivorous dinosaurs (not to mention other theropods). Of course, the most famous tyrannosaur was Tyrannosaurus rex, though less well-known genera (such as Albertosaurus and Daspletosaurus) were equally deadly. Technically, tyrannosaurs were theropods, placing them in the same larger group as dino-birds and raptors. Find out more in an in-depth article about tyrannosaur behavior and evolution.

Not the Biggest Meat-Eating Dinosaur The largest one named Scotty was discovered in Canada's Badlands. It's on display at the Royal Saskatchewan Museum in Canada. Most people assume that the North American Tyrannosaurus rex—at 40 feet from head to tail and seven to nine tons—was the biggest carnivorous dinosaur that ever lived. T. rex, however, was equaled or outclassed by not one but two dinosaurs: the South American Giganotosaurus, which weighed about nine tons, and the northern African Spinosaurus, which tipped the scales at 10 tons. These three theropods never had the chance to square off in combat, since they lived in different times and places, separated by millions of years and thousands of miles.

Arms Not as Tiny as Once Thought Some think that the small arms of T. rex were the right size for holding prey near their jaws. One feature of Tyrannosaurus rex that everyone makes fun of is its arms, which seem disproportionately tiny compared to the rest of its massive body. T. rex's arms were over three feet long, however, and may have been capable of bench pressing 400 pounds each. In any event, T. rex didn't have the smallest arm-to-body ratio among carnivorous dinosaurs; that was the Carnotaurus, whose arms looked like tiny nubs.

Very Bad Breath What is known about the four-foot jaws and mouth of Tyrannosaurus rex is it contained about 60 serrated teeth (some 12 inches long) ready for tearing meat—and its breath was most likely horrendous.The dinosaurs of the Mesozoic Era obviously didn't brush their teeth or floss. Some experts think shards of rotten, bacteria-infested meat constantly lodged in its closely packed teeth gave Tyrannosaurus rex a "septic bite," which infected and eventually killed its wounded prey. This process likely would have taken days or weeks, by which time some other meat-eating dinosaur would have reaped the rewards.

Females Bigger Than Males Scientists have trouble distinguishing whether a T-rex individual was male or female.There's a good reason to believe, based on fossils and the shapes of the hips, that the female T. rex outweighed the male by a few thousand pounds. The likely reason for this trait, known as sexual dimorphism, is that females had to lay clutches of T. rex-size eggs and were blessed by evolution with bigger hips. Or maybe females were more accomplished hunters than males, as is the case with modern female lions.

Lived About 30 Years It’s believed that some dinosaurs lived to about 150 years old, while the life span of Tyrannosaurus rex was about 30 years.It's difficult to infer a dinosaur's life span from its fossils, but based on analysis of existing specimens, paleontologists speculate that Tyrannosaurus rex may have lived as long as 30 years. Because this dinosaur was atop the food chain, it would most likely have died from old age, disease, or hunger rather than attacks by fellow theropods, except when it was young and vulnerable. Some of the 50-ton titanosaurs that lived alongside T. rex might have had life spans of more than 100 years.

Both Hunters and Scavengers Tyrannosaurus rex may have been both a hunter and scavenger. For years, paleontologists argued about whether T. rex was a savage killer or an opportunistic scavenger—that is, did it hunt its food or tuck into the carcasses of dinosaurs already felled by old age or disease? Current thinking is that there's no reason Tyrannosaurus rex couldn't have done both, as would any carnivore that wanted to avoid starvation.

Hatchlings Possibly Covered in Feathers The hatchlings were much different—about the size of a turkey and thought to be covered in feathers. It's accepted as fact that dinosaurs evolved into birds and that some carnivorous dinosaurs (especially raptors) were covered in feathers. Some paleontologists believe that all tyrannosaurs, including T. rex, were covered in feathers at some point during their lives, most likely when they hatched, a conclusion supported by the discovery of feathered Asian tyrannosaurs such as Dilong and the almost T. rex-size Yutyrannus.

Preyed on Triceratops The debate continues on T. rex's diet, but many think that Triceratops was on the menu. Imagine the matchup: a hungry, eight-ton Tyrannosaurus rex taking on a five-ton Triceratops, a not-inconceivable proposition since both dinosaurs lived in late Cretaceous North America. Granted, the average T. rex would have preferred to tackle a sick, juvenile, or newly hatched Triceratops, but if it was hungry enough, all bets were off.

Incredibly Powerful Bite Scientists continue to debate the amount of power T. rex had in its bite. In 1996, a team of Stanford University scientists examining a T. rex skull determined that it chomped on its prey with a force of 1,500 to 3,000 pounds per square inch, comparable to that of a modern alligator. More recent studies put that figure in the 5,000-pound range. (The average adult human can bite with a force of about 175 pounds.) T. rex's powerful jaws may have been capable of shearing off a ceratopsian's horns.

Tyrant Lizard King Paleontologists take into consideration the shape of hip bones as well as other body parts when naming, classifying, or grouping dinosaurs. Henry Fairfield Osborn, a paleontologist and president of the American Museum of Natural History in New York City, selected the immortal name Tyrannosaurus rex in 1905. Tyrannosaurus is Greek for "tyrant lizard." Rex is Latin for "king," so T. rex became the "tyrant lizard king" or "king of the tyrant lizards."