Dinosaurs died out about 66 million years ago, however they live on in our imagination. They populate books and toy dog shelves. They besides star on the boastfully screen in blockbuster movies like 1993 ’ s Jurassic Park and this summer ’ sulfur Jurassic World. such efforts have made us all familiar with creatures like the awful Tyrannosaurus king, the three-horned Triceratops and the long-necked Brachiosaurus .
But not all dinosaurs were huge beasts. Some were only the size of chickens. And not every prehistoric reptile was a dinosaur .
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Dinosaurs are but one small group of reptiles. Ancient ecosystems besides hosted the ancestors of today ’ randomness crocodiles, snakes, lizards and turtles. And the landscape teemed with many early types of reptiles that are now long gone. Some lived in the sea. Others took to the air and soared like birds. Some lived on farming and, at first base glance, resembled dinosaurs. But the detail features of their fossils, or ancient remains, intelligibly show they were not dinos .
“ In many cases, these animals played very important roles in their ecosystems, ” says Thomas Holtz, Jr. He works at the University of Maryland in College Park. As a vertebrate paleontologist, he studies the fossils of creatures with backbones .
many of these ancient non-dinos died out at the same time as dinosaurs. Others went extinct millions of years sooner. Scientists hush aren ’ metric ton sure why. Studying the dodo record can provide clues. It besides can show which groups of ancient creatures are most closely relate, when they first appeared and how they evolved — changed over time .
It’s all in the hips
For millions of years, dinosaur dominated many of Earth ’ mho ecosystem. The first dinos emerged in the fossil record about 235 million years ago. They disappeared some 169 million years former. Some scientists think a massive comet or asteroid strike earth and wiped them out .
Some dinosaurs were big. Others were humble. Some eat animals. Others dined entirely on plants. Some ran on two legs ; others walked on all fours. But all had at least one thing in common, notes Sterling Nesbitt. He ’ s a vertebrate paleontologist at Virginia Tech in Blacksburg. Every dinosaur had holes where its thighbones, or femurs, attached to the pelvis. “ All dinosaurs had this assailable hip socket, ” he says. “ It ’ s not found in any other reptiles. ” Simply put, reptiles lacking this hip structure were not dinosaurs .
Scientists look at traits like pelvis structure to distinguish species. Each species, whether surviving or long extinct, has its own particular set of characteristics. Birds have feathers, and mammals have hair’s-breadth. today ’ randomness reptiles have scales. Fossils suggest that most dinosaurs had scales besides. so do fish ( but their scales are different ). The more traits that two species share, the more close related they tend to be. “ By looking at shared characteristics, you can tell what creatures are related, ” says James Clark. He ’ s a vertebrate paleontologist at George Washington University in Washington, D.C .
Two examples of how scientists draw a cladogram, or family corner, for relate species. In both, species A and B are more closely related to each early than either is to C. Alexei Kouprianov/Wikimedia Commons ( CC-BY-SA 3.0 )
For living creatures, Clark notes, scientists often go beyond anatomy and consider similarities or differences in genetic material such as DNA. But for ancient animals, scientists typically have only fossils. Researchers can use those various characteristics to build a family tree. This method of mapping family trees is called cladistics (Klah-DISS-tiks).
For surviving creatures, Clark notes, scientists frequently go beyond anatomy and consider similarities or differences in genetic material such as deoxyribonucleic acid. But for ancient animals, scientists typically have only fossils. Researchers can use those assorted characteristics to build a syndicate tree. This method of mapping family trees is called cladistics ( Klah-DISS-tiks ). Cladistics reveals that many different types of reptiles lived during ancient times. In fact, the Mesozoic Era, which lasted from 252 million to about 66 million years ago, is frequently referred to as “ the Age of Reptiles. ” Among animals during that drawn-out era, reptiles dominated. But among them, dinosaurs were lone one group .
even if something looked and behaved like a dinosaur, it wasn ’ t a dinosaur unless it had the right field hip social organization. Consider a ferocious meat-eater barely described by Nesbitt and his teammates in the November 4, 2014 Journal of Vertebrate Paleontology. The team named the creature Nundasuchus ( NOON-dah-SOO-kuss ). In the local Swahili language, nunda means “ predator. ” The suffix suchus is from a greek discussion for “ crocodile. ”
Nundasuchus was probably about 2.75 meters ( 9 feet ) long. Some of its teeth had edges that were serrated, like steak knives. But this ancient meat-eater was not a dinosaur. It didn ’ t have the right hep structure. And the reptile ’ second ankle bones were alike to those of animals in a different group of reptiles, called Pseudosuchia ( SOO-doh-SOO-kee-ah ). That name is a combination of Latin and Greek words that means “ faithlessly crocodiles. ”
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Nundasuchus, which lived about 242 million years ago, looked very much like a dinosaur, yet was more closely related to crocodiles. ( White bones are the ones recovered by paleontologists. ). Virginia Tech
The researchers found the animal ’ second fossil bones in Tanzania, in southeast Africa. Those bones had been entombed around 242 million years ago. They didn ’ metric ton shape a complete skeleton, but they did include bones, or bits of bones, from about all parts of the animal. Those remains let the team measuring stick hundreds of the creature ’ s anatomic details. importantly, the scientists found a left rear leg that was very closely complete. “ I could tell this was a new species about immediately, ” Nesbitt says .
It would have belonged to a group of species that includes on-key crocodiles and their living and extinct relatives. It besides includes other groups of ancient and now-extinct reptiles. One is called the rauisuchids ( RAOW- ee-SOO-kidz ). These meat-eaters, some of which reached lengths of 6 meters ( 20 feet ), are often mistaken for dinosaurs because they look so similar. But their hips show they aren ’ triiodothyronine dinosaurs at all .
Up in the air!
Birds weren ’ t the first vertebrates to take to the skies. One group of reptiles beat them to it by a good 75 million years or more. Called pterosaur ( TAIR-oh-saurs ), these creatures take their identify from the greek words for “ wing lounge lizard. ”
Pterosaurs were close relatives of dinosaurs. Their hip structures were roughly exchangeable. Pterosaurs and dinosaurs besides are the lone groups of reptiles that have one particular musical arrangement of bones in their ankles. “ It ’ second very classifiable, ” says Clark. Yet these similarities don ’ metric ton hateful that pterosaurs evolved from dinosaurs, he explains. It just means that they both shared some common ancestor. so, on the reptile class tree, they were only cousins .
This trope depicts a giant azhdarchid pterosaur, named Quetzalcoatlus northropi. With a 10 meter ( about 33-foot ) wingspan, this reptile stood arsenic tall as a giraffe. These pterosaurs lived aboard tyrant dinosaurs and probably preyed on smaller reptiles, including this pamper Tyrannosaurus king .Mark Witton
The oldest known pterosaurs were well adapted for flying. Like birds, their bones were hollow and filled with air. That helped make their bodies light and easier to get off of the ground. But unlike birds, pterosaurs had no feathers. Instead, their wings were covered in thin membranes made of skin and other tissues. Those membranes stretched between their wings’ bones (which included a very long finger) and their bodies. Sometimes the rear edge of the wings stretched back and connected to a pterosaur’s ankles. (This past April, scientists reported finding
The oldest sleep together pterosaurs were well adapted for flying. Like birds, their bones were hollow and filled with publicize. That helped make their bodies ignite and easier to get off of the ground. But unlike birds, pterosaurs had no feathers. rather, their wings were covered in thin membranes made of skin and other tissues. Those membranes stretched between their wings ’ bones ( which included a identical hanker finger ) and their bodies. sometimes the buttocks edge of the wings stretched back and connected to a pterosaur ’ sulfur ankles. ( This past April, scientists reported finding Yi qi, a species of little dinosaur with a pterosaur-like wing membrane. But it ’ s not so far clear if that creature was truly able to flap and fly like birds and pterosaurs, the researchers say. possibly it could only glide. ) For the first 70 million years, pterosaurs remained reasonably much the lapp size, says Roger Benson. He ’ s a vertebrate paleontologist at the University of Oxford in England. All pterosaur species during that time had an average wingspan of about 1.2 meters ( 4 feet ). then, starting about 150 million years ago, pterosaurs began enlarging. And that tendency continued until the animals became extinct 66 million years ago. Near the end, the wings of diverse species spanned from 3 meters ( 10 feet ) to 10 meters ( 33 feet ) across. ( For comparison, a U.S. Air Force F-16 fighter jet has a 10-meter wingspan. )
Two things drove that increase in average wingspan. Some huge species evolved. At the same time, most minor pterosaur species vanished. This might be linked to the appearance of the first base birds, researchers suggested in 2014 in Nature Communications. And here ’ mho why : Birds and humble pterosaur probably dined on the like types of creatures. early on birds might have been more active or more agile than pterosaurs their size. So the flying reptiles might have lost out when competing with birds for a meal. In fourth dimension, these small pterosaurs largely died out. Those that survived did indeed by evolving into such huge sizes that they no longer competed with birds .
many people incorrectly call all flying reptiles “ pterodactyls. ” That identify, which comes from the greek words for “ annex feel, ” belongs to only one group of pterosaurs. They get their name from the long thin finger that supports the front edge of their wing, explains Clark. typically, a pterosaur is considered a pterodactyl if the longest bone in its wing finger is eight times longer than its diameter .
That’s just weird
Dinosaurs are well known for their unusual appearance. many had horns, spikes, plates or any of enough of early odd features. Pterosaurs could look reasonably weird excessively. Some early species had toothy jaws and long tails. many subsequently species had no tooth and about no tail .
But one pterosaur might have looked much weirder than the stay. It lived about 120 million years ago in what is now northeastern China. Adults credibly had a wingspan of about 1.5 meters ( 5 feet ). In many ways, this flying reptile looked like other pterosaurs. But its fossils provide tantalizing clues that this species was special. The presence dowry of its lower jaw had a deeply, flimsy, crescent keel of bone. Near the point where this semicircle joined the lower chew, there was a peculiar hook-shaped projection .
Its fossils were first base described in the journal Scientific Reports in 2014 .
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Flying reptiles — such as these Ikrandraco avatars — were pterosaurs, not dinosaurs. They did live during the lapp era as dinos. Fossils reveal many clues about how and when such creatures evolved, arsenic good as how they lived. These birdlike reptiles may have had a wingspan of 1.5 meters. Chuang Zhao
No other pterosaur has this classifiable feature. In fact, its discoverers say, no other vertebrate, living or long extinct, has such a bony projection. Because of that, scientists aren ’ t quite sure what purpose this hook served. It may have been an anchor for soft weave. ( Unlike bones, soft tissues rarely get preserved as fossils. ) indeed, based on where the crochet is located, the pterosaur might have had a pelican-like pouch below its lower call on the carpet. This pouch could have held fish that the pterosaur scooped up as it swooped across the surfaces of lakes or rivers .
The scientists named the new species Ikrandraco embodiment. “ Draco ” is the Latin son for dragon. The other two parts of the name come from the diagnose of the movie Avatar and the fabricated flee beasts, “ ikran, ” that were ridden by warriors in that film ’ south battles .
The lesson with this animal, as with many other ancient creatures, is that barely because something outwardly resembled a dinosaur did not mean it was one .
Next: The ancient reptiles that ruled the seas
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anatomy The study of the organs and tissues of animals. Scientists who work in this field are known as anatomists .
asteroid A rocky object in orbit around the sun. Most orbit in a region that falls between the orbits of Mars and Jupiter. Astronomers refer to this region as the asteroid knock .
cladistics An approach to biological classification in which organisms are grouped together based on whether or not they share anatomic characteristics .
comet A celestial object consist of a nucleus of ice and scatter. When a comet passes near the sunlight, gas and dust vaporize off the comet ’ south open, creating its trailing “ tail. ”
dinosaur A term that means awful lounge lizard. These ancient reptiles lived from about 250 million years ago to roughly 65 million years ago. All descended from egg-laying reptiles known as archosaurs. Their descendants finally split into two lines. They are distinguished by their hips. The lizard-hipped occupation became saurichians, such as bipedal theropods like T. king and the lumbering quadrupedal Apatosaurus ( once known as apatosaur ). A moment argumentation of alleged bird-hipped, or ornithischian dinosaurs, led to a widely differing group of animals that included the stegosaurs and duckbilled dinosaurs .
DNA ( short-circuit for deoxyribonucleic acid ) A long, double-stranded and spiral-shaped atom inside most life cells that carries genetic instructions. In all populate things, from plants and animals to microbes, these instructions tell cells which molecules to make .
doppelgänger A give voice from the german that means a double — or double — of person or some thing .
ecosystem A group of interacting living organisms — including microorganisms, plants and animals — and their physical environment within a particular climate. Examples include tropical reefs, rainforests, alpine meadows and arctic tundra .
evolution ( five. to evolve ) A process by which species undergo changes over time, normally through familial variation and natural survival. These changes normally result in a newfangled character of organism better suited for its environment than the earlier character. The newer type is not necessarily more “ advanced, ” fair better adapted to the conditions in which it developed .
extinct An adjective that describes a species for which there are no living members .
femur In humans, the bombastic bone in the upper leg. It is normally known as the femur. In tetrapods ( creatures with four limbs ), it ’ s the big bone in the upper back limbs .
fossil Any preserve remains or traces of ancient life. There are many different types of fossils : The bones and other body parts of dinosaurs are called “ body fossils. ” Things like footprints are called “ tracing fossils. ” Even specimens of dinosaur stern are fossils. The process of forming fossils is called fossilization.
genus A group of closely relate species. For model, the genus Canis — which is Latin for “ pawl ” — includes all domestic breeds of cad and their closest wild relatives, including wolves, coyotes, jackals and dingoes .
keel A structural sport that runs along the bottom of a boat ’ s hull from front to back ( stem turn to stern ) and may about look like a flipper extending down into the water. The boat ’ second glow or flooring are normally attached to this .
Mesozoic Era An interval of geological time from about 252 million to around 66 million years ago. Often called the Age of Reptiles, this earned run average includes the Triassic, Jurassic and Cretaceous periods .
paleontologist A scientist who specializes in studying fossils, the remains of ancient organisms .
paleontology The branch of science concerned with ancient, fossilized animals and plants .
pelvis Bones that make up the hips, connecting the lower spine to leg bones. There is a break in the middle of the pelvis that is larger in females than in males and can be used to tell the sexes apart .
predator ( adjectival : predatory ) A animal that preys on early animals for most or all of its food .
projection Something feature that extends out ( or projects ) from the body of a structure .
pterosaur Any of versatile extinct flying reptiles of the orderliness Pterosauria. These animals lived 245 million years ago to 65 million years ago. Although not true dinosaurs, they lived during the reign of dinosaurs. Among members of this regulate were the pterodactyl of the Jurassic and Cretaceous periods, which were characterized by wings consisting of a flap of skin supported by the very long one-fourth finger on each forelimb .
pterodactyl A group of pterosaurs that get their identify from the long slender finger that supports the presence edge of their wing. typically, a pterosaur is considered a pterodactyl if the longest bone in its wing finger is eight times longer than its diameter .
reptile cold vertebrate animals, whose skin is covered with scales or aroused plates. Snakes, turtles, lizards and alligators are all reptiles .
serrated A description for a saw-like border, normally found on knives meant to cut through baffling kernel .
trait A characteristic have of something. ( in genetics ) A quality or characteristic that can be inherited .
tyrannosaur A line of flesh-eating dinosaurs that began during the late Jurassic Period, about 150 million years ago. These species persisted into the recently cretaceous period, about 65 million years ago. The best know member of these species : the late Cretaceous ’ Tyrannosaurus king, a 12-meter ( 40 foundation ) long circus tent marauder of its clock .
Tyrannosaurus rex A top-predator dinosaur that roamed Earth during the late cretaceous period. Adults could be 12 meters ( 40 feet ) long .
vertebra ( plural vertebrae ) One of the bones that make up the neck, spine and stern of vertebrates. Bones in the neck are called cervical vertebra. Bones in the tail, for animals that have them, are called caudal vertebra .
vertebrate The group of animals with a genius, two eyes, and a cadaver boldness cord or backbone running down the back. This group includes all fish, amphibians, reptiles, birds, and mammals.
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