Dinosaur endothermy: the evidence 255 in Java Generation Code 3/9 in Java Dinosaur endothermy: the evidence 255

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Dinosaur endothermy: the evidence 255 using visual .net toencode qrcode in web,windows application Microsoft SQL Server This idea was s .net vs 2010 QR-Code trongly reinforced by the discovery in 2000 of what was controversially inferred to be a four-chambered heart with an aorta. The heart was preserved as an ironstone mass within the thoracic cavity of the basal ornithopod Thescelosaurus, and identi ed using computed tomography (a CT scan).

Doubters doubted; advocates advocated; and the issue remains unresolved.. Minds. In the late 1970s, attempts were made to assess the intelligence of dinosaurs using the encephalization QR for .NET quotient or EQ (Box 12.4).

The idea was that living endotherms (birds and mammals) have signi cantly higher EQs than do living ectotherms (reptiles and amphibians), presumably because their more re ned levels of neuromuscular control require an endothermic metabolism. EQ was reconstructed in dinosaurs using brain endocasts, internal casts of the braincases of dinosaurs (Figure 12.3).

Based upon EQ, coelurosaurs were likely as active as many birds and mammals, while large theropods and ornithopods were somewhat less active than birds and mammals, but more active than typical living reptiles. Using EQ as representative of activity levels, other dinosaurs appear to have been in the range of living reptiles..

Figure 12.3. Brain endocasts of (a) Plateosaurus (see also Figure 4.6); (b) Tyrannosaurus. (a) Cerebellum Olfactory region Cerebrum Cranial nerves (b) Cerebrum Ce rebellum Medulla oblongata Olfactory region Pituitary Fenestris ovalis Cranial nerves 5 cm Fenestris ovalis 5 cm Pituitary. Medulla oblongata The nose knows. Endothermy requires the lungs to replenish their air (ventilate) at a high rate. And high rates .net framework qr-codes of ventilation lead to water loss, unless something is done to prevent it. What modern mammals and birds do is to grow convoluted sheets of delicate, tissue-covered bone, called respiratory turbinates, in the nasal cavaties.

The mucus-covered surfaces of the turbinates pull moisture out of the air before it leaves the nose, thus conserving water (Figure 12.4). What about dinosaurs Although a number appear to have had olfactory turbinates (indicative of a well-developed sense of smell), apparently none as far as we currently know had respiratory turbinates to allow them to recoup respired moisture.

Considered exclusively on this basis, dinosaurs could not have been endothermic in the way that most mammals and birds are today.. Histology Fossil bone may visual .net QR Code 2d barcode preserve ne anatomical details that are visible under a microscope. To see the details, a thin slice can be mounted on a glass slide, and ground down so thin that light can be transmitted through it (Figure 12.

5).. Haversian bone. Bones grow by remodeling, which involves the resorption (or dissolution) of bone rst laid down primary bone and redeposition of a kind of bone called secondary 256 Dinosaur thermoregulation: some like it hot 12.4 Dinosaur smarts How can we meas ure the intelligence of dinosaurs 1 The short answer is Not easily. However, it is clear that, at a very crude level, there is a correlation between intelligence and brain : body weight ratios. Brain : body weight ratios are used because they allow the comparison of two differently sized animals (that is, brain : body weight ratios allow comparison of chihuahua and St Bernard dogs).

The correlation suggests that, in a general way, the larger the brain : body weight ratio, the smarter the organism. Indeed, mammals have higher brain : body weight ratios than sh and are generally considered to be more intelligent (Figure B12.4.

1). But how smart could a very large dinosaur with a miniscule brain be (for example, see Box 5.2) It is well known that organisms change proportions as they increase in size; this is allometry.

And it turns out that brain : body weight ratios follow allometric principles as well: brains do not increase in size proportionally to the rest of the animal. For example, the brain of a 0.5 m rattlesnake is proportionally larger than the brain of a 3 m anaconda.

Does this mean that the anaconda is signi cantly stupider than the rattler Obviously not. So, when considering how big or small a brain is in an animal, there has to be a way to compensate meaningfully for size. A quantitative method of doing this was rst proposed by psychologist H.

J. Jerison, who, in the early 1970s, developed a measure called the encephalization quotient (EQ). Jerison constructed an expected brain : body weight ratio for various groups of living vertebrates (reptiles, mammals, birds) by measuring many brain : body weight ratios among these animals.

Jerison noted that, on the basis of EQ, living vertebrates cluster into two groups, endotherms and ectotherms. The endotherms show greater encephalization (higher EQs) and the ectotherms showed lower encephalization (lower EQs). Thus, for Jerison, living endotherms and ectotherms could be distinguished by brain size.

Having constructed a range of expected brain : body weight ratios, he could account for size in different organisms (and accommodate what might at rst seem like an extraordinarily large or small brain). Noting that some organisms still didn t exactly t in his ectotherm or endotherm group (by virtue of having brains either larger or smaller than expected), he measured the amount of deviation, and then termed this EQ..

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