Why do dinosaurs have tails

It's a little confusing since the lizard hips not the bird hips, and meat-eaters in particular, were the ancestors of birds. Q: How long could a plesiosaur's neck grow to? A: Plesiosaurs not dinosaurs, but giant marine reptiles, or giant sea creatures, so I don't know much about them. The biggest of the plesiosaurs, elasmosaurus, lived in what is now Kansas and grew to 46 feet long. More than half of that — about 26 feet — was neck! Q: How big was the heart in a brachiosaurus?

A: We don't know how big the hearts of any dinosaurs were, since soft parts of the inside of their bodies don't preserve as fossils. It is likely that brachiosaurus and other big four-legged plant-eaters had huge hearts since they had to pump blood all over their vast bodies including up their long necks. I'd guess their heart was larger than you are. Guide students through their study of dinosaurs with these articles, lesson plans, online learning activities, and writing assignments.

Create a List. List Name Save. Rename this List. Rename this list. List Name Delete from selected List. Save to. Save to:. Save Create a List. Create a list. Save Back. Grades 3—5 , 6—8 , 9— View not found. Download the PDF from here. Related Subjects. Appears in This Collection. Grade s PreK If evolution can make a bird who balances perfectly without a heavy tail, why would Darwinian processes insist on giving dinosaurs such wasteful rear ends?

Go read the book. These species retained some very fishy features, like internal gills, tail fins designed for swimming, and heads that had no way to hear airborne sound waves. They did have thick, strong thigh bones femora with large joints for the hip socket and knee.

Reptiles today have that muscle, as do salamanders. Next time you are in Grand Chenier, La. The big chunk of meat you are eating is the tail-thigh muscle. It attaches to the side of the tail bones and then runs forward to attach to that bump on the thigh bone. When the tail-thigh muscle contracted in Ichthyostega , it pulled the hind limb back and pushed the body forward. In other words, the tail-thigh muscle was one of the main propulsive organs that let the earliest four-legged animals walk.

Stage Two: Early Reptiles, about million years ago. Early reptilian legs were much longer than in the early amphibs, and the beasts were far more nimble. The tail-thigh muscle still was the No. The end of the tail was very long and whip-like, so it could be used as a weapon to slap other reptiles or inquisitive amphibians who got too close.

Leg action was even stronger than in the earliest reptiles, and the tail-thigh muscle was of great size. Footprints show that most types of land crocs walked on all fours. However, the hind limbs were much, much thicker and longer than the front, so the tail-thigh muscle was dominant in thrusting the animals forward, with only a little help from the forelimb. Land crocs filled the Middle and Late Triassic with a dynamic horde of adaptive variations — we have three examples in the Morian Hall of Paleontology.

There were huge predators with heads over a yard long, armed with saw-edged fangs Postosuchus , who used their hefty tail-thigh muscles to generate fast running speeds. And there were armor-plated plant-eaters Desmatosuchus who employed their tails to brace the forequarters when the up-turned snout was busy excavating roots and tubers.

And there were immense fish-eaters with long snouts bristling with stabbing teeth up front and, in the rear, steak knife teeth for cutting prey Smilosuchus and its cousin Rutiodon. These aquatic species developed deep, flat-sided tails that were useful for swooshing underwater, providing locomotion a la croc or a la gator. Here are two land crocs featured in our Fossil Hall.

The spiky fellow is Desmatosuchus , an herbivore. The big-headed chap is Postosuchus , a predator. Our Smilosuchus is a close kin. The drawing is by the great S. Williston for his delightful book, Water Reptiles of the Past and Present. Williston did all his own illustrations — my hero! Stage Four: Carnivorous Dinosaurs, about million years ago. The first genuine dinos evolved from a quadrupedal ancestor shaped like a Land Croc. The dinos took the trends in limb evolution to extremes.

They reduced the size of the front legs even more, and increased the length and thickness of the hind. The early meat-eating dinosaurs were completely, unapologetically bipedal. Since the tail was already very heavy, it found employment balancing the forequarters.

My old professor Stephen J. The long tail of bipedal dinosaurs did NOT first evolve as a counterbalance. It first evolved in strictly quadrupedal animals, the earliest fishy-oid amphibian. The tail was the attachment for the tail-thigh muscle, a key unit of the hind limb stroke. They fed the computer simulation a digital model of the animal, taken from CT scans of its fossil bones. With the computer simulation, the researchers could divide the dinosaur's backbone into multiple segments, such as the body, head, neck, back and tail.

The researchers were then able to switch parts of the body on and off, to figure out exactly what role each part played while the simulated dinosaur sprinted from point A to point B in as little time as possible.

It turns out that the tail was doing much more than just acting as a counterbalance. When the researchers removed the tail from the simulation or kept it from moving, the dinosaur started rotating its pelvis differently to compensate for the missing or immobile tail. This suggests that the tail played an important role in controlling angular momentum, or the momentum of a rotating object.

If you think of the center of the dinosaur as the axis, the tail was working to keep the creature balanced as its body weight shifted from left to right during a run. It's the same reason "us humans swing our arms when we walk or run," Bishop said. This dinosaur, and many other bipedal dinosaurs, had small arms that didn't do much to control this dynamic balance. They also found that when they forced the tail to wag out of sync with the legs for example, having the tail move right when the dinosaur stepped its right leg forward, rather than the left leg , the dinosaur had to expend "massively" more energy, Bishop said.

This suggests that the tail also played a role in energy-efficient locomotion. Because the methods were tested and refined with living analogs, "we can be confident they work with fossil animals," Benton told Live Science in an email.

Though the researchers focused on just a single dinosaur species, they think that because Coelophysis bauri had a body design that's very similar to many other bipedal dinosaurs, the results likely hold true for those species when running. The results also likely hold true for walking dinosaurs, but the tail wagging is likely less vigorous, Bishop said.

Ibrahim was the lead author of a study published in the journal Nature in April that found one giant dinosaur, Spinosaurus aegyptiacus , may have used its tail to move through water.