The Flight and Movement of the Pterosaur and Comparison to Birds

The Flight and Movement of the Pterosaur and Comparison to Birds

Introduction to Pterosaur

Birds that are commonly known today come from an extensive line of evolution that dates back to the Mesozoic era. There are many misconceptions about the evolution of birds, including some of their ancestral relatives. One of those distant relatives that can be mistakenly classified with modern avian species, is the order Pterosauria, more specifically the species Pterodactylus. The Pterosaur, a class of winged reptiles that existed during the same time period of dinosaur, more specifically referred to as the Mesozoic Era. The Pterosaur is reptile that holds a great amount of significance in paleontological history. Being that this reptile is recognized as one of the first animals to employ flight as a means of movement, it is an early precursor to the flight we see in modern birds today. Pterosaurs belong to the order of Pterosauria (flying reptiles) in which, there are two main types of Pterosaurs that derive from different sub orders. Those are the sub orders Pterodacyloidea and Suborder Rhamphorhynchoidea. As with any classification of a kingdom, there are several genera that arise from each sub order. Although these flying reptiles existed in the same time period as dinosaurs, and are closely related, they are not considered dinosaurs by classification. They also possessed similar characteristics that are seen in modern day birds such as the ability to fly, but these reptiles share no common ancestor with modern day birds. Some of the features that distinguish the order of Pterosaur include leathery wing surface that attaches from the leg and spans to the hands, as well as teeth, claws, very large wingspan, and talons to name a few. Although this order has many characteristics that makes it very distinct in history, it also shares many common traits with modern day birds and their ancestors with traits such as similar flight evolutions and bone structures like the keeled sternum. In order to most effectively make a comparison between birds and pterosaurs, common traits among the two will be analyzed and compared. Although these two genera are completely different, and share no common ancestor, it is the goal of this research to better understand and visually comprehend the differences and similarities between the two divisions of prehistoric reptiles and modern day flying birds.

Paleontological Appearance

The Mesozoic era, named for "middle animals" in evolutionary transition, is the time period in which the pterosaur existed. Within this era are three time periods including, the Triassic, Jurassic, and Cretaceous periods, 245-208 MYA, 208-146 MYA, 146-65 MYA respectively. During the Triassic period, the first dinosaurs and mammals appeared, and the beginning and ending of this period were marked by mass extinctions. These flying reptiles appeared near the beginning of the Triassic period, and died out near the end of the late Jurassic and early Cretaceous period . During this time many species besides dinosaurs and the pterosaur came into existence and became extinct, hence this period is noted for containing many species only seen in this era.

Cladistics

Pterosaurs are derived from the kingdom Animaila, and their lineage goes as followed: phylum Chordata, Subphylum vertebrata, superclass Tetrapoda, Class Diapsids, Subclass Archosauria, and Order Pterosauria. The order that Pterosaur belong to, Pterosauria, is used to classify all flying reptiles, and includes the two suborders of pterosaurs. The first suborder, Rhamphorhynchoidea, classifies pterosaur with long tails, short necks, and long narrow wings. They are considered the first flying vertebrates and probably used their wings for powered locomotion. This suborder includes seven geuns' with an average 2.5 foot wingspan. The only exception in this genus is Campylognathoides, which possessed a wingspan of twenty feet. The majority of the pteorsaus that existed in this genus primarily ate fish and insects. The second sub order, Pterodactyloidea, includes pteorsaurs with a "wing finger" only seen in this suborder. This suborder includes the more commonly known species of Pterodactyl, and consists of the larger reptiles in Pterosauria. The reptiles in this suborder averaged a wingspan of about ten feet. This suborder also contained genus Quetzalcatlus, which was known averaging the largest wingspan in the kingdom. With a 36 foot wingspan, Quetzalacatlus was noted as the largest flying animal ever. Its features included gliding rather than flapping, a long, pointed jaw and a curved neck . In comparison to genus Pterodactylus, to birds, their phylogeny goes as followed: kingdom animalia, phylum chordate, class aves. As observed, these two genus' split fairly early in evolution when they diverged into classes. This is because, at this point, reptiles diverge from birds. According to the University of California research, "the main diagnostic physical character for diapsid is the presence of two openings on each side of the skull; the upper and lower temporal openings." This arrangement allows for the attachment of larger, stronger jaw muscles, and enables the jaw to open more widely. They also are known for a relatively long radius in comparison to their humerus Whereas the class aves is characterized by forelimbs modified into wings, lack of teeth, a bill, a four chambered heart, eggs with hard shells, and a furculum, they are also the only animals that have feathers.

Features, Powered Flight, and Flight Mechanisms

The order of Pterodactyloidea contain many distinguishing features, some of which are very distinctive to the only to the order, while others are shared among flying birds today. Some of the prominent features that distinguish the order of Pterosaur include: a leathery membranous wing that is employed by the reptile for either flying or gliding. "Fingers" were also seen in some species, where the fourth finger served as an attachment for the wing, the first three were free, and the fifth "finger" was a degenerate. Other features that were distinct to the order included the lack of feathers, the presence of a "pteroid" bone , the attachment of the wings from the animal's upper thigh all the way to the finger, as well as claws, boney tails, teeth, very large wingspans, walking on four limbs, and head horn, all seen in various combinations within the order. Features that are common to both birds and pterosaurs is actually fairly lengthy, and include the following: hollow bone structure, keeled sternum, long distance flying, similar predatory techniques, and vast range in size dependent