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The calculated temperature difference C is metabolic rate (watts) x time constant (seconds) heat capacity (joules per C) metabolism could keep themselves only a few degrees warmer than their surroundings. Elephants seem to have trouble keeping cool in Africa, and seem comfortable enough even in winter in zoos in temperature countries, which seem consistent with the entry in the table for 5-tonne dinosaurs. Those comparisons encourage me to think that the calculations may have been reasonably...

Weighing Dinosaurs

R-i-i he drawings of dinosaurs in chapter 1 were based on fossil bones, .L fitted together to form complete skeletons. These skeletons tell us how large dinosaurs were. There is no reason to suspect that the sizes of bones have been changed by the processes of fossilization. There may of course be doubts about the size of the animal if bones are missing. For example, there are doubts about how many bones are missing from the tail of Tyrannosaurus, which one palaeontologist made 3.7 meters 12 ft...

Flying Reptiles

The pterosaurs lived at the same time as the dinosaurs. Both groups appeared late in the Triassic period and became extinct at the end of the Cretaceous. Pterosaurs were winged reptiles, with astonishingly long fingers that helped to support their wings figure 8.1 . Most fossils show only the skeleton, but a few show impressions of the wings and one has marks that seem to be impressions of fur. If pterosaurs were furry they were probably endotherms, with the fur serving as heat insulation....

Dinosaur Strengths

Fossil footprints seem to tell us that large dinosaurs usually moved slowly, but could they move fast in an emergency Could they jump, and do other athletic things We expect very large animals to be lumbering monsters. Buffaloes are less nimble than gazelles and elephants are less nimble than buffaloes. Were dinosaurs that were much larger than elephants less nimble still You have to be strong to run fast or to jump. When you stand, your weight is divided between your two feet the force on each...

Dolphin Downstroke Flukes Lift Drag

Kronosaurus Size Comparison

Ichthyosaurs presumably swam in the same way. The aspect ratios of tails can be measured in the same way as for wings, by dividing the span of the tail by its mean chord figure 8.4 . High aspect ratio tails give the same lift for less drag, like high aspect ratio wings, and make for efficient swimming. Tunny tails have high aspect ratios, for example 7 for Yellowfin. Whale flukes have lower aspect ratios, for example 5 for White-sided dolphin, possibly because they...

Marine Reptiles

Great White Shark Skeleton

We will now discuss the giant reptiles that lived in the sea in the Mesozoic era, when the dinosaurs were living on land. They had flippers instead of feet and would probably have been pretty helpless on land. We know that they lived in the sea rather than in fresh water because the other fossils found in the same rocks include sea urchins and squid-like molluscs, members of groups whose modern members are found only in the sea. I am going to start with the ichthyosaurs reptiles that looked...

Ablc

Might get bogged down but big ones with longer legs might be able to walk, with their feet sinking to the firm ground. There is another complication. Different soils support loads in different ways. Wet clays depend mainly on cohesion between the clay particles, and the load they can support is about proportional to the area carrying the load. Dry sand depends mainly on friction between the grains and the load it can support is about proportional to the 1.5 power of the area that means that...

Death of the Giant Reptiles

Graphs Iridium

LL THE magnificent animals that I have been writing about became extinct at the end of the Cretaceous period, 65 million years ago. The dinosaurs died out, leaving the birds which seem to have evolved from them as their only descendants. The pterosaurs, ichthyosaurs, mosasaurs, and plesiosaurs died out leaving no descendants. Many invertebrate groups became extinct including the ammonites, marine mollusks with coiled shells which are extremely common fossils in Mesozoic rocks. The extinctions...

What Is The Volume Of A Living Triceratops In Cubic Centimeters

Sagittarius Serpentarius Anatomy

SOURCES whale Nishiwaki 1950 elephant Laws 1966 others Meinertzhagen 1938. SOURCES whale Nishiwaki 1950 elephant Laws 1966 others Meinertzhagen 1938. Colbert's method was difficult to perform accurately because it depended on the sand being leveled off precisely at the top of the box. He used it in preference to the method that I used later, because he did not want to get his valuable plaster models wet. For measurements on plastic models, I used a method that depends on Archimedes' Principle,...

Giant Mammals

Indricotherium Skeleton Reconstruction

Here were no big mammals while the dinosaurs lived but many mammals of elephant or rhinoceros size evolved during the Ceno- The best known of the giant extinct mammals were the mastodons and mammoths. Mastodons are primitive elephants, distinguished by their simple teeth. Mammoths are much more like modern elephants. Both survived to overlap in time with humans, and many cave paintings of mammoths have been found. The biggest mammoth species Mammuthus imperator of North America stood 4 meters...

Abc

Forces on the foot and tibia of Tyrannosaurus. Diagram a shows the leg skeleton, the force on the sole of the foot and the muscles that extend the ankle b shows all the important forces on the foot and c shows forces on the lower end of the tibia. I faced all these questions in my research on moas, the giant ostrichlike birds that are discussed in chapter 11. Here we avoid facing them directly by making the general assumption, that the movements of dinosaurs and the stresses...

Dinosaur Necks and Tails

Reared Barosaurus

Almost all dinosaurs had long tails and some also had long necks. In an extreme case, Diplodocus had a neck 7 meters 23 ft long including the small head , a tail about 14 meters 46 ft long and body only 5 meters 16 ft long. This chapter asks how dinosaurs used long necks and tails. I will start with necks. The longest are those of sauropods, which include the largest of all dinosaurs. Before the calculations about bone strength had been done, many people doubted whether the biggest sau-ropods...

Dinosaur Footprints

Chiroptera Footprint

OF ALL that remains of dinosaurs, their footprints bring the animals most vividly to life. Fossil bones may remind us of a rotting carcass, but footprints are evidence of a living, moving animal. It may seem incredible that dinosaur footprints should be preserved. The chances of an individual footprint surviving are remote, but millions of dinosaurs made footprints every day, for millions of years. For some, the improbable happened they survived and were found by inquisitive people. Figure 3.1...

Giant Birds

Argentavis Magnificens

Archaeopteryx, the oldest known bird, lived in the Jurassic period, quite early in the time of the dinosaurs. It was only about the size of a magpie and no giant birds appeared until the Tertiary, after the dinosaurs had gone. The teratorns were birds of prey that lived in America then. Figure 11.1 will give you an impression of their size b shows the wing bones of a Californian condor, one of the largest modern birds of prey d shows the wing bones of the Wandering albatross, which has the...

Fighting and Singing Dinosaurs

Ceratopians

R n he tails mentioned at the end of chapter 5 are not the only weap-X ons that dinosaurs had. I will now tell about horns and reinforced heads, and about how they may have been used for fighting. I also speculate about how dinosaurs may have approached rivals, and about the noises they may have made. It seems likely that male dinosaurs fought rival males of the same species, much as stags fight with their antlers and male antelope fight with their horns. It may seem odd that animals fight,...

Introducing the Dinosaurs

Dinosaurs And Mountains

This chapter tells what dinosaur fossils are like and how they are formed and introduces some of the best-known dinosaurs. It is an introductory chapter intended mainly for readers who have little previous knowledge of these remarkable reptiles. Other may prefer to skip quickly through the chapter or to go directly to chapter 2. Figure 1.1 shows a dinosaur 13 meters 43 feet tall, well over twice the height of a full-grown 5.5 meter giraffe. It is far bigger than any modern land animal and its...

Scale Mammals Mass Body Femur Anderson

Femur Mammals

A graph showing humerus circumference plus femur circumference plotted against body mass, for various quadrupedal mammals. Data from Anderson et al. 1 985. FIGURE 2.5. The same data as in figure 2.4 re-plotted on logarithmic scales, with additional points, including one for Brachiosaurus. FIGURE 2.5. The same data as in figure 2.4 re-plotted on logarithmic scales, with additional points, including one for Brachiosaurus. the circumferences of their bones. However, appearances can be...