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Sep 14 2010
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Prehistoric Reptiles

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Prehistoric Reptiles; Anything But the Dinosaur

Prehistoric Pteranodons FlyingThe term prehistoric reptiles is generally used to refer to prehistoric creatures that fit in to the reptile category but were not “dinosaurs” per say. The term “prehistoric reptiles” encompasses a broad range of creatures broken down by category.

What Are Prehistoric Reptiles?

The categories that make up the broader term of prehistoric reptiles are as follows:

  • Pelycosaurs, Archosaurs andTherapsids
  • Pterosaurs
  • Ichthyosaurs
  • Plesiosaurs and Pliosaurs
  • Crocodiles
  • Mosasaurs and Prehistoric turtles

The Four Biologic Subclasses of Prehistoric Reptiles

The various categories of prehistoric reptiles are distinguished in four various biological subclasses:

  1. Anapsida
  2. Diapsida
  3. Synapsida
  4. Euryapsida

Anapsida

The Anapsida are a category of reptile that have skulls that lack holes on the side of their skulls much like modern day turtles – a common day Anapsida is the Loggerhead Turtle.

Diapsida

The Diapsida are categorized by the two arches that appear in the sides of the skull of the reptile. The two holes within the skull allow for stronger muscles in the jaw because they offer more anchor points for the muscle tissue to attach to.

Synapsida

The Synapsida have one opening on the lower side of the skull and generally categorize creatures that appear to be mammal like.

Euryapsida

The Euryapsida have one opening on the higher side of the skull and include marine reptiles. In short the skull of a reptile is what categorizes which subclass the reptile is placed in.

When Did Prehistoric Reptiles Exist? How Long Did They Live?

Prehistoric reptiles like the Pelycosaurs, Archosaurs and Therapsids existed some tens of millions of years before the Tyrannosaurus Rex and walked the Earth for approximately 120 million years, all the way through to the mid Triassic period. The Pelycosaurs walked the Earth from the late Carboniferous to the early Permian periods. These huge land animals were only primitive versions of the reptiles that they were later to become as they developed mammal like qualities. One of the most recognized Pelycosaurs was the Dimetrodon known for the frilled spine that ran along its back. Other Pelycosaurs include the Casea, Cotylorhynchus, Ctenospondylus, Edaphosaurus, Haptodus, Ianthasaurus, Mycterosaurus, Ophiacodon, Secodontosaurus, Sphenacodon and Varanops.

Triassic Period Prehistoric Reptiles: The Archosaurs

The Archosaurs were the prehistoric reptiles of the Triassic period and dominated the Earth until the larger dinosaurs stepped in to the picture. One of the most well known Archosaurs is the Arizonasaurus who resembles the Dimetridon in appearance and hails from Arizona. Other Archosaurs include Asilisaurus, Batrachotomus, Chasmatosaurus, Desmatosuchus, Dinocephalosaurus, Effigia, Erthrosuchus, Euparkeria, Hyperodapedon, Lagosuchus, Lotosaurus, Marasuchus, Mystriosuchus, Ornithosuchus, Poposaurus, Prestosuchus, Protorosaurus, Saurosuchus, Sharovipteryx, Silesaurus, Teratosaurus, Ticinosuchus, and Trilophosaurus.

Permian Period Prehistoric Reptiles: The Therapsids

The Therapsids were mammal like reptiles that evolved from previous reptiles in the middle Permian period. The Therapsids lived during the same years as the early dinosaurs. One of the most well known Therapsids is the Hipposaurus that bore little resemblance to its common day mammal namesake. Other Therapsids include Anteosaurus, Biarmosuchus, Cistecephalus, Cynognathus, Deuterosaurus, Dicynodon, Diictodon, Dinodontosaurus, Dinogorgon, Estemmenosuchus, Gorgonops, Jonkeria, Kannemeyeria, Lycaenops, Lystrosaurus, Moschops, Phthinosuchus, Placerias, Pristerognathus, Procynosuchus, Raranimus, Robertia, Sinokannemeyeria, Styracocephalus, Tapinocephalus, Tetraceratops, Theriognathus, Thrinaxodon, Titanophoneus, Titanosuchus, Trirachodon, Ulemosaurus.

Pterosaurs: The Flying Prehistoric Reptiles

Prehistoric reptiles like the Pterosaurs are most well known as the flying reptiles of the prehistoric era. As the first animals to fly these winged creatures followed their land dwelling creature’s footsteps and evolved throughout the prehistoric periods to become much more advanced and much larger creatures than they initially began as. The first Pterosaurs appeared on Earth during the mid to late Triassic period which occurred 230 – 200 million years ago and were much smaller than the later Pterosaurs which evolved in the late Cretaceous period. Early Pterosaurs are distinguished by their small size as well as bones that exist within their wings. Examples of early Pterosaurs include the Eudimorphodon, Dorygnathus and Ramphorhynchus.

Flying Prehistoric Reptiles the Size of Airplanes!

As Pterosaurs evolved in to the late Jurassic period they became larger creatures known as Pterodactyloid Pterosaurs. The Pterodactyloid Pterosaurs had both bigger wings than their ancestors and shorter tails. As they continued to evolve through the Cretaceous period the Pterosaurs grew in to the gigantic Azhdarchids that grew so large in fact that paleontologists who study their skeletal remains question whether or not they could have feasibly flown. Some of these monster Pterosaurs include the Tapejara, the Tupuxuara, the Quetzalcoatlus and the Zhejiangopterus. Wingspans of these huge beasts ranged from 16 feet to an enormous 30 feet wide! In comparison to other dinosaurs the Pterosaurs had more advanced coordination centers than their less intelligent dinosaurs which perhaps enabled their much better vision used during hunting. One interesting fact in regard to the Pterosaurs is that some of the species showed signs of having primitive hair which indicates that they were more related to warm-blooded mammals than previously thought. Some examples of Pterosaurs include: Aetodactylus, Dimorphodon, Dorygnathus, Eudimorphodon, Germanodactylus, Nyctosaurus, Pteranodon, Pterodactylus, Sordes, and Thalassodromeus.

Prehistoric Reptiles of the Sea

The Fish Lizards

Prehistoric reptiles like the Ichthyosaurs are referred to as the “fish lizards” because of their resemblance to modern day fish in both body and behavior. Some paleontologists believe that Ichthyosaurs evolved from the archosaurs that made their move back in to the sea during the Triassic period. Early Ichthyosaurs were, for the most part small and did not have dorsal fins or water dynamic bodies. As the Ichthyosaurs continued to evolve, however, by the end of the Jurassic period the majority of them had vanished with the exception of the Platyptergius which managed to survive through to the early Cretaceous period.

It is the belief of paleontologists that the Platypterygius survived so much longer than its cousins due to its evolution that allowed it to survive on an omnivorous diet. Despite being reptiles the Ichthyosaurs were believed to have performed live births rather than lay eggs, however, their lack of gills and existence of lungs gives more credit to them being of reptilian class. Some examples of Ichthyosaurs include the Californosaurus, Cynbospondylus, Eurhinosaurus, Excalibosaurus, Grippia, Ichthyosaurus, Mixosaurus, Omphalosaurus, Ophthalmosaurus, Platypterygius, Shonisaurus, Stenopterygius, Temnodontosaurus and Utatsusaurus.

The Sea Serpents

Prehistoric reptiles like the Plesiosaurs and Pliosaurs are also known as the “sea serpents”. The Plesiosaurs and Pliosaurs swam the Earth during the Mesozoic era and a fraction of people today still hold that Plesiosaurs and Pliosaurs still swim in the world’s water! The Plesiosaurs were characterized by their four flippers and long necks and they fed on fish for the most part. Since they were actually reptiles rather than fish the Plesiosaurs and Pliosaurs both had to surface to breathe air to survive. Paleontologists also speculate that the long necks on these reptiles were to assist in more efficient fishing. Unlike Plesiosaurs the Pliosaurs were much larger and were certainly not as gentle nor strictly fish eaters. Pliosaurs possessed sharp teeth rather than the sifting apparatus that the Plesiosaurs had which indicates that they fed on marine life as well as fish.

Since both Plesiosaurs and Pliosaurs lived in the ocean their skeletal remains are often found in a singular formation thanks to the protective qualities of the ocean’s silt. Some examples of the Plesiosaurs include the Attenborosaurus, Aristonectes, Elasmosaurus, Hydrotherosaurus, Kronosaurus, Libonectes, Macroplata, Mauisaurus, Plesiosaurus, Rhomaleosaurus, Styxosaurus, Terminonator, Thalassiodracon, Thililua and Woolunfasaurus. Some examples of the Pliosaurs include the Liopleurodon, Crytoclidus, Dolichorhynchops, Leptocleudus, and the Megalneusaurus.

Rulers of the Sea: The 50 Foot Long, 15 Ton Mosasaurs

Prehistoric reptiles like the Mosasaurs were sleek predators of the water who are thought to be one of the reasons for the extinction of the Ichthyosaurs. These hydrodynamic creatures were built for speed and agility and as such they proved to be competition not just for the Ichthyosaurs but also for the Plesiosaurs and the Pliosaurs too. As a result of their predatory nature and pushing their competitors within the water out of their territory and beating them to food supplies the Mosasaur became the ruler of the sea for nearly 20 million years until the catastrophic event that brought the end of the dinosaurs. It is believed that initially the Mosasaur evolved from land dwelling creatures similar to monitor lizards or even snakes due to their long sleek bodies. Mosasaurs varied in length and size and could be 14 feet long and a few hundred pounds or 50 feet long and 15 tons!

The size difference between various Mosasaurs can be accounted for by variation in diet which could range from small fish to large sea turtles! Some examples of Mosasaurs include Clidastes, Dallasaurus, Eonatator, Globidens, Hainosaurus, Halisaurus, Mosasaurus, Platecarpus, Plioplatecarpus, Plotosaurus, Prognathodon and Tylosaurus.

Prehistoric Reptiles of Today: Crocodiles

Baby Crocodile SmilingPrehistoric reptiles like the Crocodiles are still roaming the Earth today; however, thankfully these beasts have changed considerably since then! Much like the Pterosaurs the Crocodiles are thought to be descended from the Archosaurs. The feature of the Crocodiles that makes them so different from the dinosaurs of prehistoric times is the shape of their jaws and their limbs which were not straight like other dinosaurs of the time.

Prehistoric Crocodiles in the Jurassic Period

Early crocodiles were relatively small and lived on land, some even fed on all vegetarian diets! As Crocodiles evolved in to the Jurassic period they began to move in to the water and develop the characteristics that we recognize as Crocodilian – long bodies, long snouts with powerful jaws and splayed limbs. As they continued to evolve much like the Pterosaurs they grew to extreme proportions and approached monster size closing in at 40 feet long and 10 tons in weight.

Crocodiles Survive the Mass Dinosaur Extinction

The biggest distinction between other prehistoric reptiles and the Crocodiles is that there is absolute proof that these creatures made it through the catastrophic event which brought an end to other prehistoric reptiles and dinosaurs. Crocodiles today maintain many of the distinguishing characteristics of their prehistoric ancestors. Some examples of prehistoric Crocodiles include Bernissartia, Chimaerasuchus, Deinosuchus, Desmatosuchus, Doswellia, Erpetosuchus, Geosaurus, Gracilisuchus, Metriorhynchus, Mystriosuchus, Protosuchus, Rutiodon, Sarcosuchus, Simosuchus, Stagonolepis, and Stomatosuchus.

Prehistoric Turtles Also Continue To Live Today

Prehistoric reptiles like the prehistoric turtles tell the story of the complete evolutionary process of a reptile since it continues to thrive in today’s modern society.

Prehistoric Turtles in the Triassic Period

Over the years, since the turtle appeared for the very first time during the late Triassic period, the turtle body shape and anatomy has changed very little. Paleontologists aren’t too sure what reptile initially grew in to the turtle but they have found similarities in the Eunotosaurus, a reptile with wide ribs that cover the back much like the shell of the turtle. It is also believed that the early prehistoric turtles had teeth and as they evolved they gradually developed less and less teeth until they had none at all.

By the Jurassic period turtles had their bodies and very little changed as far as the shape, however, when it comes to size the turtles of prehistoric times have some rather large shoes to fill! The large turtles which evolved during the Cretaceous period – what seems to be the time of gigantism-were not only larger but they possessed significantly larger flippers for propelling their larger bodies through the waters. Of all the turtles that swam through the prehistoric era the most notable is the Stupendemys which weighed in at two tons and pulled its head in to its shell sideways rather than in an in and out motion.

Some more examples of prehistoric turtles include Archelon, Colossochelys, Eileanchelys, Eunotosaurus, Henodus, Meiolania, Odontochelys, Placochelys, Proganochelys, Protostega, and Psephoderma.

Prehistoric Reptiles: Bridging The Prehistoric and Modern Worlds

While they may have differed from the dinosaurs of the times, the Pelycosaurs and Archosaurs and Therapsids, Pterosaurs, Ichthyosaurs, Plesiosaurs and Pliosaurs, Crocodiles, Mosasaurs and Prehistoric turtles certainly had a lot to share with the prehistoric world - and in some cases our modern world as well. It may be a common misconception that the prehistoric reptiles were smaller and more timid creatures when compared to the dinosaurs of their time. This is, however a misconception because the truth of the matter is that during the Cretaceous period when many of these prehistoric reptiles cohabited with dinosaurs these reptiles dwarfed many of the dinosaurs that lived alongside them.

Gigantism and Survival of the Mass Extinction

When gigantism set in among many of the reptiles of the Cretaceous era they were as much a force to be reckoned with as were the land roaming dinosaurs! It should also be taken in to consideration that many of these “simple” reptiles survived a significantly traumatizing event that managed to wipe out some of the much larger and much more terrifying dinosaurs of the time.

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What came before pelycosaurs, archosaurs, and therapsids?

Exactly just HOW far back, can we go to know what existed? We had dinosaurs yes, and pelycosaurs, archosaurs, and therapsids. But what came before those too? Basically, what WAS THE very first living thing ON Earth?

Microscopic organisms

The very first things to live on Earth are believed to be single cell prokaryotes, found in the Abiogenesis, or primordial soup.

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