 |
 |
 |
 |
 |
 |
 |
 |
 |
 |
 |
 |
 |
 |
 |
 |
| Sauropsida |
| The
first animals and plants to invade land required water
to complete their live cycles. Spore producing plants such
as lycopsids, horsetails, and ferns need wet environments
so that sperm can swim to and fertilize eggs. Amphibian
eggs must be laid in moist conditions that allow the tadpole,
fish-like, larval stage to live and develop in an aquatic
environment.
Evolutionary Innovations Evolutionary innovations that appear in the Carboniferous period would free plants and animals from a life cycle tied to water. As we have already discussed, seed plants delivered sperm to eggs via wind carried pollen. Seeds provided plant embryos with an independent life support unit, which provided nourishment and protection from dry conditions. Among tetrapods the reptile-like amphibians would give rise to the amniotes that reproduced on dry land delivering sperm via internal fertilization. Amniotes evolved an independent life support unit for their embryos in the form of the amniotic or cleidoic egg. Amniotic
Egg Amniote Skulls Several amniote evolutionary lines are documented by temporal fenestrae, openings in the skull behind the eye. These holes function to reduce use of bone and provide additional edges for jaw muscle attachment. Anapsid amniotes (subclass Anapsida) have no temporal fenestrae and include turtles and most of the earliest reptiles. Diapsid amniotes (subclass Diapsida) have two temporal fenestrae and include lizards, snakes, crocodiles, dinosaurs, pterosaurs, sphenodonts and the extinct marine reptiles (formerly grouped as the subclass Euryapsid). Euryapsids have one upper temporal fenestra. Synapsid amniotes (class Synapsida and class Mammalia) have one lower temporal fenestra and include protomammals (formerly referred to as mammal-like reptiles) and mammals. Reptiles were the first amniotes and appear in the Carboniferous. The subclass Anapsida and Diapsida are in the reptilian class Sauropsida. The First Reptiles The first reptiles (class Sauropsida) were small lizard-sized tetrapods living in damp forests of the mid-Carboniferous feeding on insects and worms. In Nova Scotia there are sedimentary deposits that contain upright lycopod tree stumps. Since 1852 thirty Sigillaria tree stumps have produced abundant tetrapod remains. These tetrapods were living in the rotted out Sigillaria trunks. Hylonomus and Paleothyris are two tetrapods that were preserved in the hollow tree stumps and represent the oldest known amniotes (Benton, 2005, pp 110-111). Reptiles remained relatively small during the Carboniferous and into the Permian. Multiple new families of anapsid type reptiles appear in the Early Permian. We will mention just a few. Reptiles
& Continental Drift Bipedal Tetrapods Members of the family Bolosauridae are rather rare. However, the bolosaurid Eudibamus, from the Early Permian, has the distinction of being the first known bipedal tetrapod. This slender reptile had a long tail, long hindlimbs, and short forelimbs. The teeth of Eudibamus suggest a diet of tough plant material. Walking Upright Members of the family Pareiasauridae were large, heavily built herbivores. Pareiasaurs had their legs placed underneath their body, so they could walk more upright. Pareiasaurus and Scutosaurus were typical members of the family reaching lengths of 8ft. Glidding Reptiles Diapsids remained at low diversity during the Early Permian, but underwent an adaptive radiation in the Late Permian. Coelurosauravus (Family Weigeltisauridae) was a small lizard-like diapsid with a very interesting adaptation. The ribs of this weigeltisaurid could fold out forming wing-like structures. This organism could have glided from tree to tree like the living lizard Draco does. Archosaurs Another important diapsid group, which makes its first appearance in the late Permian, is the archosaurs (Infraclass Archosauromorpha). While some archosaurs had the standard reptilian sprawling gate (limbs directed sideways) others evolved a more erect posture. Archosaurs with erect postures had legs that were placed more directly under the body, an important terrestrial adaptation. A more erect posture increases stride length. Legs tucked beneath the body can support the organisms weight with less stress.Archosaurs would undergo a great adaptive radiation during the Triassic. One group of archosaurs would give rise to two evolutionary lines one, leading to the crocodilians the other, to pterosaurs, dinosaurs, and birds (Benton, 2005, pp. 138-143). Diapsid reptiles would come to rule the land, sea, and air during the Mesozoic. Dinosaurs Sir Richard Owen (1804-1892), a British comparative anatomist and paleontologist, created the taxon Dinosauria to describe large terrestrial reptiles that walked upright, clearly different from other fossil or living reptiles. He based Dinosauria on the grouping of three taxa including Megalosaurus, Iguanodon, and Hylaeosaurus. The Dinosauria were inaugurated in an 1842 published version of an 1841 lecture given to the British Association for the Advancement of Science in Plymouth (Padian, 1997, p. 175).Dinosaurs (Superorder Dinosauria "terrible or fearfully great lizards") range from the Triassic to the Cretaceous (to the present if you include birds). The oldest dinosaurs, like Coelophysis, were small bipedal, carnivorous organisms. Dinosaurs diversified into many forms and came to dominate terrestrial faunas during the Jurassic and Cretaceous. In 1887 Harry Seeley (1839-1904), a British paleontologist, proposed that Dinosauria could be divided into two groups based on their hip structure, braincase, and vertebrae (Padian, 1997, p. 494). Seeley's scheme has persisted to this day. The order Saurischia includes dinosaurs with a lizard-like hip structure. The order Ornithischia includes dinosaurs with hip structures reminiscent of birds. Representatives from both groups appear in the Triassic period, although Ornithischians remained relatively rare until the Jurassic. Saurischian
Dinosaurs Theropods Coelophysoids Ceratosaurs Tetanurans Carnosaurs Carnosaurs are the first well-known tetanurans and were large predators. Megalosaurus ("great lizard") was a 9 meter long carnosaur that ranges from Early to Late Jurassic. Megalosaurus was the first dinosaur to be scientifically named and described in the 1820's. It was one of the creatures that prompted Sir Richard Owen to coin the term Dinosauria in 1841.At 12 meters long, 4.6 meters tall, and up to 2 tonnes, Allosaurus ("different lizard") was the largest carnosaur of the Late Jurassic. Joints in the upper and lower jaws allowed Allosaurus to wolf down large chunks of flesh. Allosaurus was equipped with more than seventy teeth up to 7 cm long and three sharp claws up to 25 cm long on each forelimb. Horn-like structures were located above and in front of each eye (Lessem & Glut, 1993, pp. 19-20). Allosaurus is the state fossil for Utah. Saurophaganax maximus is an Allosaur-like theropod that is the state fossil for Oklahoma. Coelurosaurs Coelurosaurs
are a diverse clade of theropods that are more closely
related to birds than to the carnosaurs. Coelurosaurs
include the tyrannosaursids (formerly grouped with
carnosaurs) of the Late Cretaceous, ornithomimids,
and maniraptorans. The suborder Sauropodomorpha includes both the prosauropods and the sauropods. In general, they are herbivorous quadrupeds with a small head, long neck, large body with legs tucked beneath, and a long counterbalancing tail. The small head contained jaws with lanceolate or spatulate teeth used for stripping vegetation from branches. Food was ground in the gizzard by gastroliths. Their pillar-like legs supported a deep body to accommodate an enormous digestive system. Sauropodomorphs had five-toed, spreading feet. They possessed a large thumb claw that was probably used for digging and no claws on fingers 4 and 5. Sauropodomorphs had large nostrils set higher on the skull than most vertebrates. Although basal sauropodomorphs were bipedal omnivores the evolutionary trend in this group was towards quadrupeds of increasing size. To accommodate ever larger sizes the vertebrae evolved with increasing bone pneumaticity (hollow spaces). Bone was developed only along the lines of stress. The massive pelvic girdle became firmly fused to the backbone by 4 and later 5 sacral vertebrae. The spaces in these bones may have been filled with air sacs connected to the lungs as in modern birds. These hollowed out bones with air sacs would have reduced weight and enhanced respiratory efficiency (Benton, 2005, p. 202). Plateosaurus ("flat lizard"), of the Late Triassic, is the best known and largest prosauropod. Plateosaurus was 8 meters long and could adopt either a bipedal or quadrupedal posture. Gizzard stones have been found in the upper rib cage of specimens. The abundance of reamins suggest a herding behavior for this early dinosaur. Several Late Jurassic sauropods are familiar to many people. Camarasaurus ("chamber lizard") is the best- known sauropod from North America. This 18 meter long compact browser had a relatively short neck and tail. The forelimbs were only slightly shorter than the hindlimbs. Camarasaurus had a box-like skull with large nasal openings. Camarasaurus had heavy, spoon-shaped teeth that could handle tough plant material. Adults and juveniles have been found in the Morrison formation indicating they traveled in herds. Within these deposits are found isolated piles of polished stones, which may represent regurgitated gizzard stones. The eggs of Camarasurus may have been laid in lines instead of nests. Apatosaurus ("deceptive lizard") was once known as Brontosaurus ("thunder lizard"). Othniel Charles Marsh (1831-1899), an American paleontologist, described two specimens as separate animals; Apatosaurus in 1877 and Brontosaurus in 1879 (McIntosh, 1990, p. 349). Later, it was realized that the two specimens represented separate species of the same genus. Apatosaurus was the first genus given, so by taxanomic convention it is the name used. Apatasaurus was 21 meters long and up to 30 tonnes. For almost one hundred years the skull of Camarasaurus was used as a model for Apatosaurus. The relatively small head of Apatosaurus was found in 1975. The teeth of Apatosaurus were all at the front of the mouth and served to rake foliage off branches. Like most sauropods Apatosaurus had five toes on each foot. The front foot had a large claw on the thumb, while each back foot had 3 claws. Each ankle joint had thick wedges of weight-bearing cartilage. The long whip-like tail in many sauropods like, Apatosaurus, may have been used for defense as well as a counter balance to the long neck. Brachiosaurus ("arm lizard") was one of the tallest and largest sauropods, designed for reaching high in the trees. Brachiosaurus was up to 25 meters long, 16 meters tall, and weighed in at 80 tonnes. Unlike other sauropod families Brachiosaursids had front legs that were longer than the hind legs. The neck of Brachiosaurus accounted for half of its height. The humerous was enormous accounting for over 2 meters of the animal's height and giving it the name "arm lizard". Brachiosaurus had a relatively short tail and the whole body sloped down from its highest point at the shoulders, not unlike the modern giraffe. The vertebrae were marvals of engineering with large hollowed out spaces on the sides making a lightweight framework that provided maximum strength along the lines of stress with a minimum amount of bone (Dixon, 1998, p. 129). Pleurocoelus is a brachiosaurid and the state dinosaur for Texas. The Cretaceous-aged sauropod, related to Brachiosaurus, Astrodon johnstoni is the state dinosaur for Maryland. Ornithischian Dinosaurs Ornithischian
dinosaurs have a pelvic girdle in which the pubis
runs back parallel to the ischium. There is also
a prepubic
process pointing forwards. Ornithischians were all
herbivorous dinosaurs and possessed a
predentary bone, which is a beak-like bone in front
of the lower jaw. The predentary bone is matched
with the premaxilla or the rostral (in ceratopsians)
in the upper jaw.
These bones helped Ornithischians clip
vegetation. Ornithischians possessed cheek teeth
that are inset into the jaw, suggesting they had
fleshy cheeks for holding food (Prothero, 1998, p.
372). Ornithopods Ornithopods
("bird feet") were the most diverse and
successful group of ornithischians and included the
heterodontosaurids,
hypsilophodontids,
iguanodontids,
and hadrosaurids. Pachycephalosaurs Pachycephalosaurs ("thick head lizard") are the dome-headed dinosaurs. These bipedal herbivores range in size from 1 to 5 meters long. Fossils of thickheaded dinosaurs are restricted to the Cretaceous. In one specimen of Pachycephalosaurus wyomingensis the skull was 22 cm thick. The thickened skull bones of Pachycephalosaurs suggest to many that they engaged in a head-butting behavior not unlike moder day bighorn sheep (Sues, 1997, p. 512). Ceratopsians Ceratopsians
("horned faces") are a diverse group of ornithischians
from the Late Cretaceous. Ceratopsians have a triangular
shaped skull when viewed from above and a beak-like rostral
bone on the upper jaw that meets with the predentary
bone on the lower jaw. Ceratopsians evolved neck frills
and
horns. Later forms also had skeletons adapted for galloping. Stegosaurs Stegosaurs
are known mainly from the Late Jurassic. Stegosaurs
have small heads, massive bodies, and rows of alternating
bony plates that extend down either side of the backbone.
Their heavy tail is equipped with pairs of long,
sharp spikes. Stegosaurs hindlimbs are much longer
than their forelimbs, which hint at a bipedal ancestry.
Ankylosaurs Ankylosaurs arose in the Mid-Jurassic and diversified during the Early Cretaceous. Hylaeosaurus ("belonging to the forest lizard") is the earliest known primitive ankylosaur (nodosaur) and was named by Gideon Mantell in 1832. It was the third kind of dinosaur to be named and one of the specimens considered by Richard Owen when erecting the term Dinosauria. Nodosaurs are primitive ankylosaurs without tail clubs. Ankylosaurus ("curved lizard") is the largest known ankylosaur and survived to the end of the Cretacous. Ankylosaurus was up to 10 meters long and weighed in at 3.6 tonnes. The body was broad (up to 5 meters wide) and squat supported by powerful legs. Ankylosaurs had a massive bony club at the end of their tail, which would have made a formidable weapon. Dinosaur Physiology Paleontologists continue to examine evidence concerning the physiology of dinosaurs. Debate continues as to whether or not dinosaurs were endothermic (“warm-blooded”) organisms, maintaining a constant body temperature from a high metabolism or ectothermic (“cold-blooded”), relying on external, environmental sources of heat. Robert Bakker provided multiple lines of evidence in favor of viewing dinosaurs as endotherms. Benton (2005, pp. 219-223) outlines the evidence. Paleoclimate & Dinosaur Distribution Dinosaur remains are found in both northern and southern Polar Regions. Dinosaurs above latitudes of 60 degrees would need to migrate if they were ectotherms. The dinosaur fossils found in Alaska and Southern Australia are ambiguous concerning physiology because they could have been migrating seasonally. Predator-Prey Ratios Warm-blooded organisms consume 10 times as many calories as cold-blooded organisms. Thus, there is a metabolic cost for being an endotherm, one must consume greater amounts of food. The need to consume more food affects predator-prey ratios. One hundred antelope could be used to sustain one warm-blooded lion or ten cold-blooded crocodiles (Benton, 1984, p. 151). Robert Bakker found that present day spiders and the Permian carnivore Dimetrodon had predator-prey ratios of 25% or more. Fossil mammals and dinosaurs have predator-prey ratios of between 1 and 5%. Benton (2005) points out that these ratios seem to vary with the size as well as thermoregulatory state (p. 220). Erect Gait & High Speeds The erect stance, like that found in dinosaurs, is today found only in living endotherms (birds and mammals). Fossil trackways suggest that dinosaurs could achieve high speeds, especially small bipedal forms. Haemodynamics Haemodynamics is the study of blood flow or circulation. Long-necked dinosaurs, like Brachiosaurus, would need an efficient, strong heart to push well-oxygenated blood to the brain. Many argue you would need a four-chambered heart like a mammal for this kind of a job and that the three-chambered heart of most reptiles would not suffice. Other scientists point out that possessing a four-chambered heart is not necessarily evidence of endothermy; crocodilians are ectothermic and possess a four-chambered heart. Bone Histology Dinosaur bones are highly vascular, unlike modern reptiles. Many dinosaurs have haversian canals like that found in mammals. However, some small birds and mammals with high metabolic rates lack haversian canals. Fibrolamellar bone found in many dinosaurs is a compact, fast-growing bone formed without growth rings. This bone is also found in large, fast growing mammals and some birds. However, lamellar-zone bone that grows slowly, forming growth rings is also found in some dinosaurs and modern reptiles. Growth Rates Dinosaurs, like large mammals, were fast growers achieving adult size in only a few years; even large sauropods reached maturity in 10 to 15 years. Modern reptiles grow slowly. Insulation Benton (2005) points out that Bakker was ridiculed when he suggested that some dinosaurs might have feathers (p. 221). It is now known that feathers evolved in theropods. The insulation provided by feathers is an indication of endothermy. Core & Peripheral Temperatures Oxygen isotope ratios of O-18/O-16 in peripheral versus core bones can be correlated to body temperature. Analysis of dinosaur bones seems to be consistent with endotherms, while crocodilians from the same time period are consistent with present day ectotherms. Turbinates Modern birds and mammals have thin nasal bones called turbinates that function to recapture water from exhaled air. Modern ectotherms and dinosaurs lack turbinates. Size & Body Temperature Some scientists argue that large sauropods were homeotherms, they maintained constant body temperatures by virtue of being large. Many
of these arguments taken alone can be regarded as
ambiguous
concerning the possibility of endothermy
in dinosaurs. As a young person interested in science,
what impressed me most about Robert Bakker’s case
for warm-blooded dinosaurs was the fact that he employed
multiple lines of evidence. For example, dinosaurs with
low predator to prey ratios are also the ones with fast
growing bone and high average walking speeds (Bakker,
1986, p. 392). I am sure that paleontologist will find
new ways to test ideas about dinosaur metabolism in the
future. Pterosaurs (Order Pterosauria "winged reptile") were the first vertebrate fliers and range from the Late Triassic to the Late Cretaceous. Pterosaurs are not dinosaurs, but they are close relatives. These flying reptiles had wings of skin connecting the entire length of the body and thigh to the forelimbs, which extended out some distance due to a greatly elongated fourth finger. Pterosaurs occupied many of the same habitats dominated by living birds and ranged from sparrow size to giants with 12-meter wingspans. Pterosaurs are divided into two groups. Rhamphorhynchs (suborder Rhampho-rhynchoidea) range from the Late Triassic to the Late Jurassic. Pterodactyles (suborder Pterodactyloidea) range from the Late Jurassic to Late Cretaceous (Padian, 1997, p. 614). This classification will most likely change as the Rhamphorhynchoidea is a paraphyletic group. Rhamphorhynchs ("beak snouts") were the first group of pterosaurs to evolve. Eudimorphodon ("true dimorphic tooth") appears in the late Triassic and exhibits many of the characteristics of the group. Eudimorphodon’s wings, like all pterosaurs, were made of membranous skin attached along the length of the elongated fourth finger and connecting back along the body to the level of the thigh. Wing-like skin also attached the wrist bones and neck. In addition to the elongated fourth finger the hand was equipped with three short grasping fingers. The foot had five long toes. A vertical, diamond-shaped flap of skin adorned the tip of the tail and was probably used as a rudder in flight. Eudimorphodon had two types of specialized teeth for capturing and consuming fish. A recently discovered pterosaur, Darwinopterus modularis, from the Middle Jurassic of China represents a transitional fossil linking primitive long-tailed pterosaurs and more advanced short-tailed pterodactyls (Lu, Unwin, Jen, Liu, & Ji, 2009, p. 1). The genus Darwinopterus (“Darwin’s Wing”) is for Charles Darwin, honoring the 2009 anniversaries of his birth (200 years) and the publication of On the Origin of Species (150 years). The species name modularis is Latin for “composed of interchangeable units”. The species name focuses on a key aspect of this transitional fossil. Darwinopterus does not exhibit characteristics intermediate between basal pterosaurs and derived pterodactyloids; rather, it possesses the body and limbs of a primitive pterosaur and the head and neck of a pterodactyloid. This mosaic of primitive and derived characteristics provides evidence for modular evolution. Natural selection may have acted on modules instead of individual characteristics. In the first phase of pterosaur evolution the head elongated, teeth were reduced, the braincase enlarged, and the neck became more flexible. In the second phase, body and limbs modifications improved locomotion on the ground (Lu et al., 2009, p. 6). A genetic basis for modular selection may ultimately be found in the study of regulatory genes or homeotic genes. Regulatory genes such as Hox genes are found in all multicellular organisms and control the development of body plans and organ systems. A small change in Hox genes can produce a significant change in body plan (Prothero, 2007, p. 102). Pterodactyls
("winged finger") are the best-known flying
reptiles. Pterodactyls had the same general structure
as the
rhamphorhynchs;
however, the tail was shorter, the neck longer and
the skull more elongate. Pteranodon ("wing
toothless") is one of the largest and best-known
pteranosaurs. Pteranodon had
a wing span of up to 8 meters and was probably a
glider. A crest on the back of the head doubled the
skull length. The crest may have acted as stabilizer
during flight, although it was sexually
dimorphic. The jaws of Pteranodon were toothless,
which is unusual for a pterosaur. Pteranodon may
have fed on fish like the modern Pelican. The cervical
vertebrae had pneumatic foramen that served
to reduce
weight
and increase respiratory efficiency. Marine Reptiles A variety of marine predators hunted fish and cephalopods in the Mesozoic seas. Pterosaurs and crocodilians fed on fish near the surface. The main reptilian predators were the ichthyosaurs, sauropterygians and finally the mosasaurs. Ichthyosaurs Ichthyosaurs (Infraclass Ichthyosauria) range from the Triassic to the Cretaceous. Ichthyosaurs and sauropterygians have a euryapsid type skull. Euryapsids have a single upper temporal opening and use to be placed in their own subclass. It is now believed that the euryapsid skull pattern arose from diapsids that lost the lower temporal opening (Benton, 1997, p.641). Ichthyosaurs
possessed
streamline bodies not unlike tuna, had long snouts
and large eyes. Ichthyosaurs filled a niche similar
to modern day dolphins and ranged in lengths from
1 to 16 meters. Ichthyosaurs were air-breathing reptiles
that propelled themselves quickly through the water
with a powerful tail. These reptiles were
so specialized for aquatic life that they gave birth to live young
in their marine habitat. The stomach contents of ichthyosaurs include
fish scales, hooklets from the arms of cephalopods
and in one specimen, from the late Cretacous, a primitive
turtle hatchling and bird. Sauropterygians Sauropterygians (Superorder Sauropterygia) range from the Triassic to the Cretacous and include the placodonts and nothosaurs of the Triassic and the plesiosaurs and pliosaurs of the Jurassic and Cretaceous. Placodonts were the least specialized reptilian swimmers; some evolved turtle-like shells. The evolution of these turtle-like shells is a good example of convergent evolution as placodonts and turtles evolved from different reptilian lines. Many placodonts specialized in eating shellfish. Nothosaurs had streamlined bodies with long necks and tails. Most nothosaurs had webbed feet, while others had flippers. Nothosaurs ate fish. Plesiosaurs (order Plesiosauria) make their first appearance during the Triassic, but do not become well established until the Jurassic. Plesiosaurs can be divided into two major groups. Plesiosaurs (suborder Plesiosauroidea) have long necks, short heads and paddle-like flippers. Plesiosaurs fed on fish and cephalopods. Pliosaurs (suborder Pliosauroidea) had short necks, long heads, and paddle-like flippers. Pliosaurs fed on fish, cephalopods, sharks, ichthyosaurs, and even plesiosaurs. Plesiosaurus (early
Jurassic) used its flippers to quickly maneuver and
its long neck to snatch swimming fish. Muraenosaurus (late
Jurassic) had a neck and flippers that were longer
than Plesiosuarus. The elongation of the neck and
flippers along with an increase in the rigidity of
the body was the evolutionary trend in plesiosaurs. Mosasaurs Mosasaurs
(Order Squamata) became important shallow marine
predators in the Late Cretaceous. Mosasaurs ("Meuse
river lizard") were air-breathing
lizards adapted for a marine life that looked somewhat
like a crocodile with flippers. Mosasaurs have an
elongate body, deep
tail,
paddle-like fins, and large skulls lined with sharp
conical teeth. Mosasaurs ranged in length from 2
to 10 meters and ate fish and other marine animals.
Mosasaurs were so fully adapted to a aquatic life
that they
gave birth to live young in their marine habitat. Platecarpus and Plotosaurus are
two mosasaurs found in the Late Cretaceous chalk
deposits of Kansas.
Ammonite shells have been found with mosasaur tooth
marks. Mass Extinction The
largest mass extinction at the end of the Permian
period provided reptiles with the opportunity to
become the dominant vertebrate life forms on Earth.
Roughly, one hundred and eighty-six million years
later the second largest mass extinction would take
away Mesozoic reptilian dominance and usher in the
Cenozoic, an age for mammals. Scientists at the University of California at Berkeley including Luis and Walter Alvarez, Frank Asaro, and Helen Michel discovered an iridium anomaly in a fine-grained clay layer in several K-T (Cretaceous/Tertiary) boundary sites around the world (now the Cretacous/Paleogene boundary). The group recognized that iridium is abundant in stony meteorites and proposed that the fallout from a meteorite on the order of 10 kilometers could explain the anomaly and possibly the extinction event. Subsequently, a crater was found beneath the Gulf of Mexico off the Yucatan Peninsula during exploration for oil. The Chicxulub crater is of the right size and age. Volcanic activity may also act as a source of iridium. The Deccan Traps in India represent a large terrestrial flood basalt. Ironically, the Deccan Traps would have been positioned on the opposite side of the Earth at the time of the Chicxulub impact. There is also evidence for climatic changes as well as floral and fauna changes leading up to these events (Stanley, 1987, pp. 133-171). Science Olympiad Fossil Event The
2016 Science Olympiad Fossil List includes ichthyosaurs (order Ichthyosauria), plesiosaurs (order Plesiosauria), mosasaurs (family Mosasauridae), and pterosaus (order Pterosauria) under the class Reptile.
|
Bibliography |
Bakker, R.T. (1986) The Dinosaur Heresies: New Theories Unlocking the Mystery of the Dinosaurs and Their Extinction. New York: William Morrow and Company, INC. Benton, M.J. (1984). The Dinosaur Encyclopedia: A Handbook for Dinosaur Enthusiast of All Ages! New York: Simon & Schuster. Benton, M.J. (1997). Reptiles. In Currie, P.J. & Padian, K. [Eds]. Encyclopedia of Dinosaurs (pp. 637-642). New York: Academic Press. Benton,
M.J. (2005) Vertebrate Palaeontology [3rd Edition].
Blackwell Publishing: Main, USA. Hooper
Virtual Paleontological Museum (1996). Extinctions: Cycles
of Life and Death Throught Time. Lu, J., Unwin, D.M., Jin, X., Liu, Y., Ji, Q. (2009) Evidence for modular evolution in a long-tailed pterosaur with a pterodactyloid skull. Proceedings of The Royal Society Biological Sciences, pp 1-7. (doi: 10.1098/rspb.2009.1603). McIntosh,
J.S. (1990). Sauropoda. In Weishampel, D.B., Dodson, P.,
& Osmolska, H. [Eds]. The Dinosauria (pp.
345-401). Berkeley: University of California Press. Padian, K. (1997). Ornithischia. In Currie, P.J. & Padian, K. [Eds]. Encyclopedia of Dinosaurs (pp. 494-498). New York: Academic Press. Padian, K. (1997). Pterosauria. In Currie, P.J. & Padian, K. [Eds]. Encyclopedia of Dinosaurs (pp. 613-617). New York: Academic Press. Palmer,
D. (1999). Atlas of the Prehistoric World. New York:
Discovery
Books. Prothero, D.R. (2007). Evolution: What Fossils Say and Why It Matters. New York: Columbia University Press. Sarjeant, W.A.S. (1997). Cyrstal Palace. In Currie, P.J. & Padian, K. [Eds]. Encyclopedia of Dinosaurs (pp. 161-164). New York: Academic Press. Siegel,
L. (2000). The Five Worst Extinctions in Earth's History. Sues,
H.-D. (1997). Pachycephalosauria. In Currie, P.J.
& Padian, K. [Eds]. Encyclopedia of Dinosaurs (pp.
511-513). New York: Academic Press. Wellnhofer, P. (1991). The Illustrated Encyclopedia of Pterosaurs. New York: Cresent Books. |