Physiological Adaptations of the Plesiosaur for ‘Holding its Breath’
One hundred and fifty million years ago, large aquatic species of reptile such as the Plesiosaur dominated the ocean, and were pre-eminent predators of the sea. The branch of now extinct Plesiosaurs, or ‘near lizards’, evolved into variant closely related species specialised to take different niches in the food chain. Such species of Plesiosaur include the phenotypically similar Plesiosauroid and Pliosauroid. The physiological adaptations of the long necked variant, the Plesiosauroid, as it relates to deep sea diving, will be addressed in depth.
Oxygen breathing lungs are a universal trait of class reptilia. As such, it would have been necessary for the Plesiosauroid - a marine reptile, to return to the ocean surface to inhale air. Oxygen expenditure in reptiles is proportional to strenuosity of locomotion (Frappell, Schultz & Christian, 2002). Therefore the Plesiosauroid must have held physiological traits that enabled the species to avoid oxygen deficit while hunting deep-sea dwelling prey. This essay will outline the hypothesised respiratory, circulatory, pulmonary and sensory attributes of the Plesiosauroid as they relate to diving. These hypotheses will be supported by investigating the physiological adaptations of the Plesiosaur’s biological analogues, and the prospect of similar adaptations in the former will be speculated upon.
Reptiles have a low metabolic rate: they consume energy, and therefore oxygen, slowly. According to Robinson (1975), Plesiosauroids were enduring swimmers with lower flipper aspect ratios and drag-causing long necks. Massare (1988) made the same conclusion, since the hydrodynamic properties of the Plesiosauroids indicate the species moved no faster than 2.3 metres every second. Therefore, the species was confronted by a conundrum: it sought to dive hundreds of metres to hunt its prey yet was constrained, by virtue of its body shape, to travel at slow speed. Invariably, the animal would have been required to forgo oxygen for periods of more than a minute, while keeping the presence of mind to hunt.
Fortunately, when making its descent of hundreds of metres, the Plesiosauroid would have been able to exploit traits possessed by many of the reptile class. Many reptiles hold the ability to temporarily slow their heart rate to reduce their oxygen consumption, via bradycardia. This effect may be caused by low temperatures, such as is found deeper in the ocean, or may be voluntarily triggered by the animal.
There would be no need for the Plesiosauroid to retain all of its oxygen-consuming faculties during the long descent.
The respiratory system is the system for taking in oxygen and giving off carbon dioxide in organisms. The respiratory systems of California sea lions, king cobras, and bald eagles have a few similarities and differences, but they all allow the intake of oxygen for each organism.
Metabolic rate is directly linked to the core temperature in an animal. An ectotherm, or cold blooded animal, warms its body mainly by absorbing heat from its surroundings. The amount of heat it derives from its metabolism is negligible. In contrast, endotherms derive most or all of its body heat from its own metabolism (Campbells,p899). Because ectotherms do not produce their own heat, they cannot actively ensure their ideal temperature for an ideal metabolic rate (aquacult.htp).
Study done from the available fossils show that the body of Liopleurodon was very streamlined and adapted to swimming. Its body had four limbs which were paddle-like in shape. These paddle shaped limbs acted like propellers which made it
Paul, Gregory S. (2002). "Looking for the True Bird Ancestor". Dinosaurs of the Air: The Evolution and Loss of Flight in Dinosaurs and Birds. Baltimore: Johns Hopkins University Press. pp. 171–224. ISBN 0-8018-6763-0.
The background of this article gives information that is necessary to understand the experiment. The shape of the pelvic girdle is an appropriate predictor of both phylogeny and movement in terrestrial vertebrates. However, in marine vertebrates, the gravitational forces typically applied to terrestrial pelvic girdles are not there and therefore have little impact on the shape of the girdle. Pelvic girdles of fish are generally not attached to the vertebrae and primarily are used as a place for muscles to attach and supporting of the fins. The authors discuss how in many cases the pelvic girdle could be removed and not result in any complications. However, there are some marine vertebrates that are capable of bottom walking on the ocean floor with their fins. In batoids, the pelvic fins are used for walking, which is when pelvic fins move in an alternating fashion, or punting, when both pelvic fins move at the same time. There is also augmented punting; this is when the vertebrate uses both the pectoral fins and the pelvic fins to generate more thrust, this action decreases the forces on the pelvic fins during a punt. While this locomotion would
The discovery of Willo is unique because it is the first dinosaur with a fossilized heart. However, this was just the beginning of an extraordinary find. “Not only does this specimen have a heart, but computer enhanced images of its chest strongly suggest it is a four-chambered, double-pump heart with a single systemic aorta, more like the heart of a mammal or bird than a reptile,” according to Dr. Dale Russell. Russell is a paleontologist at North Carolina State University and a senior research curator at the N.C. Museum of Natural Sciences. This discovery is unusual because all modern reptiles, except the crocodile, contain a single ventricle that pumps blood to the lungs and the rest of the body. All modern reptiles have paired systemic aortas developing from the ventricle, which distributes the blood to the body. “In contrast, the four chambered heart of modern birds and mammals has two completely separated ventricles and a single systemic aorta, ensuring that only completely oxygenated blood is distributed to the body” (Fisher 2).
J. G. M. Thewissen and his colleagues changed the way in which scientists thought about the early lifestyles of whales. The evolution of the ancient artiodactyls was discovered to be joined with the well-known group of cetaceans. The tertiary period was a time of terrestrial life forms. Every mammal walked the earth. It wasn’t uncommon to see a whale running through the grasslands or shark sleeping on the coast of a land mass. It was a time when mammals roamed freely and unconfined by the limits of the ocean. Now that scientists have this newly found knowledge, it is time the scientists further investigate “why?”
Audesirk, Teresa, Gerald Audesirk, and Bruce E. Byers. Biology: Life on Earth with Physiology. Upper Saddle River, NJ: Pearson Education, 2011. 268-69. Print.
The origin of modern day whales, a mystery that has puzzled paleontologists for years, may have just been solved with the discovery of an ankle bone. This discovery might sound simple and unimportant, but the bones of these ancient animals hold many unanswered questions and provide solid proof of origin and behavior. The relationship between whales and other animals has proven to be difficult because whales are warm-blooded, like humans, yet they live in the sea. The fact that they are warm-blooded suggests that they are related to some type of land animal. However, the questions of exactly which animal, and how whales evolved from land to water, have remained unanswered until now.
Hummingbirds have evolved certain behavioural and physical traits which allows for them to be more energetically efficient, such as specialized storage and digestion adaptations, feeding and flying adaptations and breathing adaptation. Hummingbirds are extremely small and their muscles for flight are highly oxygen-dependent and require large amounts of energy. Hummingbirds are one of the smallest endotherms and any energetic output can be metabolically stressful. The hummingbirds’ small body size means that they have very little room for energy storage and therefore often endure energetic and metabolic stresses. They are the one of the oldest aves, dating back to some 33 million years ago and have evolved certain energy efficient adaptations that have allowed for them to live so long. These adaptations allow Hummingbirds to efficiently meet their energetic needs which in turn, allows for them to not only survive but also continue to evolve and expand their specific niches.
Fox, R. 2001. Invertebrate Anatomy OnLine: Artemia Franciscana. Lander University. http://webs.lander.edu/rsfox/invertebrates/artemia.html, retrieved February 13, 2011.
For this experiment, it is important to be familiar with the diving reflex. The diving reflex is found in all mammals and is mainly focused with the preservation of oxygen. The diving reflex refers to an animal surviving underwater without oxygen. They survive longer underwater than on dry land. In order for animals to remain under water for a longer period of time, they use their stored oxygen, decrease oxygen consumption, use anaerobic metabolism, as well as aquatic respiration (Usenko 2017). As stated by Michael Panneton, the size of oxygen stores in animals will also limit aerobic dive capacity (Panneton 2013). The temperature of the water also plays a role. The colder the water is, the larger the diving reflex of oxygen.
Recently in an article from Elasmo.com, recognition for Mike Everhart’s discoveries has been noticed. Paleontologists and Archeologists in Western Kansas “have been finding sources of some of the best Cretaceous marine fossils that have ever been found anywhere in the world.” (Everhart, #1). These fossils, though interesting and vast, have pointed a lot of questions to how and when Kansas was under sea level. From my research, I have found that the only explanations to these issues and debates are the discoveries found consisting of both the archaic sharks and plesiosaurs.
The platypus also has webbed feet which makes it easier to swim. Its nostrils are on top
Dolphin fossils have been found dating back to 45-50 million years ago, which was during the early Eocene epoch era. The early dolphin or Protosetidae, back then did not resemble today’s dolphin. It is suggested that a primitive mammal called Mesonychidae roamed the planes of Africa. This mammal started to become more dependent on the ocean and swamps abundance of food. Researchers believe the dolphin went through an amphibious stage, similar to the seals. They would feed in the ocean and come upon land to breed.