Pintada Kid And Dinosaurs (university, living, move)

[Pintada Kid]

Dinosaurs died like 65 million years ago. Does anyone know Why? Does anyone know if they were Cold Blooded or Warm Blooded animals? Someone mentioned that there are no Dumb questions so i thought i would ask. el pintada kid

[54-60&285]

[SIZE=+2]HOT-BLOODED OR COLD-BLOODED?[/SIZE] [SIZE=+1] The debate about whether dinosaurs were hot- or cold-blooded is quite controversial. It used to be assumed that dinosaurs were cold-blooded like their reptile ancestors. Some paleontologists have recently argued that at least some dinosaurs were fast, active, competed against hot-blooded mammals, lived in cool areas, were related to birds, and therefore were endothermic (generating their own body heat, or hot-blooded). [/SIZE]

Definitions:

• Hot-blooded animals (homeotherms) generate heat internally and maintain a relatively constant body temperature (higher than the average temperature of the environment). Examples include the mammals (including people) and birds. A related term is endothermy, meaning that an organism generates their own heat to maintain body temperatures.
• Cold-blooded animals (poikilotherms) have a body temperature that changes with external conditions. Examples include reptiles, who need to sun themselves in the morning to warm up, and then protect themselves in the midday heat. A related term is ectothermy, meaning that an organism uses external heat sources (and heat sinks) to regulate its body temperature.

[SIZE=+1]Dinosaurs evolved from cold-blooded animals (the reptiles) and evolved into warm-blooded animals (the birds). All dinosaurs, however, were not the same, and perhaps their physiologies differed also. The huge dinosaurs and the tiny dinosaurs might have used different heat-regulation strategies, just as they used different strategies for other aspect of living. A good argument for this is found among modern mammals. Although warm-blooded, there are some mammals (monotremes, the egg-laying mammals like the duck-billed platypus) whose metabolisms are close to being cold-blooded. [/SIZE]
[SIZE=+1]Scipionyx, a Cold-Blooded Theropod?
Scipionyx samniticus was a Cretaceous period theropod (from about 113 million years ago), perhaps a maniraptor. It is known from a single, extremely detailed specimen of a hatchling that includes fossilized soft tissues, including muscles and internal organs. It was 9.5 inches (24 cm) long and had a very large head. [/SIZE]
[SIZE=+1]John A. Ruben, a vertebrate paleobiologist from Oregon State University, used an 80-watt ultraviolet (UV) lamp to help reveal outlines of Scipionyx's fossilized internal organs. Ruben found that the position of Scipionyx's colon (intestines) and liver were similar to that of modern crocodilians (which are cold-blooded), and unlike that of birds (which are warm-blooded). The position of the liver also gives information about the lungs, since a muscle that runs by the liver helps the lungs to expand and contract in crocodilians. Scipionyx probably had reptilian-style lungs (and not highly efficient bird lungs). [/SIZE]
[SIZE=+1]Although Ruben's work is not absolutely conclusive, it looks like the small theropod Scipionyx may be cold-blooded. For more information on Ruben's work, see the January 22; 283: 514-516 (1999) issue of the magazine Science. [/SIZE]
[SIZE=+1]A Fossilized Dinosaur Heart Found
Recently, a fossilized dinosaur heart was discovered. This powerful, four-chambered pump belonged to Thescelosuarus, a lated Cretaceous Period ornithopod (a plant-eater). This 66 million year old heart has recently been analyzed -- it may have four chambers and a single aorta, which is quite different from existing reptiles, but is similar to modern warm-blooded animals. However, Tim Rowe, Earl McBride and Paul Sereno think that the "heart" is an ironstone concretion. [/SIZE]
[SIZE=+1]If true, the discovery of a four-cha,bered heart suggests not only that Thescelosaurus may have been warm-blooded, but that many other dinosaurs may have been warm-blooded as well. This is because we now perhaps have evidence of warm-bloodedness in both Ornithischia and Saurischia (the two major groups of dinosaurs, which diverged early in the Mesozoic Era). Thescelosaurus was an ornithischian; birds, which are known to be warm-blooded, are saurischians.

Heat-Regulating Devices: Some dinosaurs seem to have had heat regulating structures on their bodies. For example, Spinosaurus and Ouranosaurus had large sails on their backs, and Stegosaurus had numerous plates. These devices were probably used for the collection and dispersion of heat. This suggests that they needed these structures to regulate their body heat and that they were cold-blooded. [/SIZE]
[SIZE=+1]Basically, it's difficult to answer this question with today's knowledge. There are a lot of people thinking about this, and we'll be hearing a lot more about it soon. [/SIZE]

[dracul]

Well done 54! Saved me the trouble of looking all this stuff up! Kudu's.

[GregW]

Modern birds are descendants of and related to one of the dinosaur groups. The dinos were one of the more sucessful groups of animals and would probably still be around if the Earth had not been in the way of a small asteroid. Just to add to everyone's anxiety lever there are still a lot of asteroids out there. God has not run out of rocks.

[Pintada Kid]

The Asteroid couldnt have killed all the Dinosaurs i would think the Plant Eaters ran out of Leafs and Starved or got eaten by the Meat Eaters and the Meat Eaters died when they ran out of food and also the Cold conditions unless the meat eaters knew how to migrate thousands of miles south for the winter and then go north to Forage in the Summer. I would think that some Dinosaurs couldnt survive the below zero temps but then the earth was lots warmer years ago. el pintada kid

[GregW]

Basically the Kid is right. There was a major "Nuclear Winter" that probably shut down most vegatation for a decade or so. Plant eaters starve, plant eater eaters starve and when things return to normal the smaller critters evolve to fill the available nitches.

[Goodpasture]

Not only did nuclear winter occur, it caused temperatures to drop to subzero in a matter of hours. Remove the sun for a few days, and you will have arctic temperatures over most of the world by the end of the week. Some equatorial areas and hot spring areas and deep water are all nearly immune from the immediate impact of the loss of the sun, which is why there are some decendents of dinosaurs still around. Things like sharks, alligators, sturgeon, birds, kimono lizards, etc still exist because they were in areas that allowed them to survive the initial onslaught of nuclear winter.

[GregW]

Goodpasture - Excellent point but sharks, sturgeon, alligators and birds were contemporaries or predate dinos. Sharks have been around essentially unchanged (don't fix what ain't broke) for 300 million years of so. Sturgeon and ‘gators may be nearly as old.

Your description of the climate change is pretty accurate. The climate also had to contend with the huge volcanoes that created the Deccan Traps on the Indian subcontinent.

[54-60&285]

Probably the most popular theory right now is the Asteroid Theory. According to this theory a large asteroid or comet collided with Earth about 65 million years ago. Scientists think that such a large collision would throw so much dust into the air that sunlight would not be able to shine and plants and animals would die. The dramatic changes in climate that resulted from this huge collision were too much for the dinosaurs. They were not able to survive. Another theory that could explain how the dinosaurs became extinct is volcanic activity. A huge increase in volcanic activity at around 65 millions years ago could have pumped so much ash into the air that it blocked out the sun killing the dinosaurs. Some scientists believe that there was a severe ice age. Throughout Earth's history there have been many ice ages. The last one ended about 10,000 years ago. A very severe ice age could have changed temperatures and frozen a lot of Earth's water. The dinosaurs would not be able live under such conditions and that is how the dinosaurs became extinct. It has also been suggested that disease killed off the dinosaurs. A very deadly and contagious disease may have circulated among the dinosaurs forcing them to become extinct. Still yet another theory is that the Earth just gradually changed in climate over a long time period and the dinosaurs were not able to adapt to the cooler, dryer climate. There are probably other theories as to how the dinosaurs became extinct. One thing is for certain. All dinosaurs that we know of are extinct. How did all the dinosaurs become extinct? Maybe one of these theories is the right answer. However, it is difficult to explain why all the dinosaurs died out but many other animals survived. Perhaps one day we will know for certain how the dinosaurs became extinct. Until then we must speculate and continue the search for the answer to this great mystery of nature.

[Vinegaroon]

It's because they were too big for Noah to put them on the Ark.