Macroevolution comprises the evolutionary processes and patterns which occur at and above the species level. In contrast, microevolution is evolution occurring within the population(s) of a single species. In other words, microevolution is the scale of evolution that is limited to intraspecific (within-species) variation, while macroevolution extends to interspecific (between-species) variation. The evolution of new species (speciation) is an example of macroevolution. This is the common definition for 'macroevolution' used by contemporary scientists. Although, the exact usage of the term has varied throughout history.
A tetrapod is any four-limbed vertebrate animal of the superclass Tetrapoda. Tetrapods include all extant and extinct amphibians and amniotes, with the latter in turn evolving into two major clades, the sauropsids and synapsids. Some tetrapods, such as snakes, legless lizards, and caecilians, have evolved to become limbless via mutations of the Hox gene. Nevertheless, these limbless groups still qualify as tetrapods through their ancestry, and some retain a pair of vestigial spurs that are remnants of the hindlimbs.
Amniotes are tetrapod vertebrate animals belonging to the clade Amniota, a large group that comprises the vast majority of living terrestrial and semiaquatic vertebrates. Amniotes evolved from amphibious stem tetrapod ancestors during the Carboniferous period and further diverged into two groups, namely the sauropsids and synapsids, an event that marks the appearance of Amniota, according to the definition established under the PhyloCode. This basal divergence within Amniota has been dated by molecular studies at 310–329 Ma or 312–330 Ma, but the presence of Hylonomus at Joggins implies a minimal age of about 317 Ma. A fossilized birth-death process study of early amniotes suggested an age of 322–340 Ma. Amniotes are distinguished from the other living tetrapod clade — the non-amniote lissamphibians — by the development of three extraembryonic membranes, thicker and keratinized skin, and costal respiration. Additional unique features are the presence of adrenocortical and chromaffin tissues as a discrete pair of glands near their kidneys, which are more complex, the presence of an astragalus for better extremity range of motion, the diminished role of skin breathing, and the complete loss of metamorphosis, gills, and lateral lines.
The Lepidosauria is a subclass or superorder of reptiles, containing the orders Squamata and Rhynchocephalia. Squamata also includes lizards and snakes. Squamata contains over 9,000 species, making it by far the most species-rich and diverse order of non-avian reptiles in the present day. Rhynchocephalia was a formerly widespread and diverse group of reptiles in the Mesozoic Era. However, it is represented by only one living species: the tuatara, a superficially lizard-like reptile native to New Zealand.
Buccal pumping is "breathing with one's cheeks": a method of ventilation used in respiration in which the animal moves the floor of its mouth in a rhythmic manner that is externally apparent. It is the sole means of inflating the lungs in amphibians.
A forelimb or front limb is one of the paired articulated appendages (limbs) attached on the cranial (anterior) end of a terrestrial tetrapod vertebrate's torso. With reference to quadrupeds, the term foreleg or front leg is often used instead. In bipedal animals with an upright posture, the term upper limb is often used.
Robert "Bob" Lynn Carroll was an American–Canadian vertebrate paleontologist who specialised in Paleozoic and Mesozoic amphibians and reptiles.
David Burton Wake was an American herpetologist. He was professor of integrative biology and Director and curator of herpetology of the Museum of Vertebrate Zoology at the University of California, Berkeley. Wake is known for his work on the biology and evolution of salamanders as well as general issues of vertebrate evolutionary biology. He has served as president of the Society for the Study of Evolution, the American Society of Naturalists, and American Society of Zoologists. He was a member of the American Association for the Advancement of Science, the Linnean Society of London, the American Academy of Arts and Sciences, the American Philosophical Society, and in 1998 was elected into the National Academy of Sciences. He was awarded the 2006 Leidy Award from the Academy of Natural Sciences of Philadelphia.
Evolutionary physiology is the study of the biological evolution of physiological structures and processes; that is, the manner in which the functional characteristics of organisms have responded to natural selection or sexual selection or changed by random genetic drift across multiple generations during the history of a population or species. It is a sub-discipline of both physiology and evolutionary biology. Practitioners in the field come from a variety of backgrounds, including physiology, evolutionary biology, ecology, and genetics.
Pharyngeal jaws are a "second set" of jaws contained within an animal's throat, or pharynx, distinct from the primary or oral jaws. They are believed to have originated as modified gill arches, in much the same way as oral jaws. Originally hypothesized to have evolved only once, current morphological and genetic analyses suggest at least two separate points of origin. Based on connections between musculoskeletal morphology and dentition, diet has been proposed as a main driver of the evolution of the pharyngeal jaw. A study conducted on cichlids showed that the pharyngeal jaws can undergo morphological changes in less than two years in response to their diet. Fish that ate hard-shelled prey had a robust jaw with molar-like teeth fit for crushing their durable prey. Fish that ate softer prey, on the other hand, exhibited a more slender jaw with thin, curved teeth used for tearing apart fleshy prey. These rapid changes are an example of phenotypic plasticity, wherein environmental factors affect genetic expression responsible for pharyngeal jaw development. Studies of the genetic pathways suggest that receptors in the jaw bone respond to the mechanical strain of biting hard-shelled prey, which prompts the formation of a more robust set of pharyngeal jaws.
Matthew Bonnan is an American paleobiologist, a Professor of Biological Sciences at Stockton University, and as of 2021 a singer/songwriter. His research combines traditional descriptive and anatomical study with computer-aided morphometric analysis and modeling of vertebrate skeletons, and he is the co-discoverer of three new species of dinosaurs. He is the author of the book The Bare Bones: An Unconventional Evolutionary History of the Skeleton, designed to introduce undergraduates and curious lay readers to the anatomy and evolution of the vertebrate skeleton. Bonnan has a music/art outreach project, Once Upon Deep Time, a pop/rock song cycle about the evolution of hearing and our connection to the tree of life.
Goniopholididae is an extinct family of moderate-sized semi-aquatic neosuchian crocodyliformes. Their bodyplan and morphology are convergent on living crocodilians. They lived across Laurasia between the Middle Jurassic and the Late Cretaceous.
Aquatic feeding mechanisms face a special difficulty as compared to feeding on land, because the density of water is about the same as that of the prey, so the prey tends to be pushed away when the mouth is closed. This problem was first identified by Robert McNeill Alexander. As a result, underwater predators, especially bony fish, have evolved a number of specialized feeding mechanisms, such as filter feeding, ram feeding, suction feeding, protrusion, and pivot feeding.
Susan Elizabeth Evans is a British palaeontologist and herpetologist. She is the author or co-author of over 100 peer-reviewed papers and book chapters.
Most bony fishes have two sets of jaws made mainly of bone. The primary oral jaws open and close the mouth, and a second set of pharyngeal jaws are positioned at the back of the throat. The oral jaws are used to capture and manipulate prey by biting and crushing. The pharyngeal jaws, so-called because they are positioned within the pharynx, are used to further process the food and move it from the mouth to the stomach.
X-ray motion analysis is a technique used to track the movement of objects using X-rays. This is done by placing the subject to be imaged in the center of the X-ray beam and recording the motion using an image intensifier and a high-speed camera, allowing for high quality videos sampled many times per second. Depending on the settings of the X-rays, this technique can visualize specific structures in an object, such as bones or cartilage. X-ray motion analysis can be used to perform gait analysis, analyze joint movement, or record the motion of bones obscured by soft tissue. The ability to measure skeletal motions is a key aspect to one's understanding of vertebrate biomechanics, energetics, and motor control.
Christine Marie Janis is a British palaeontologist who specialises in mammals. She is currently based at the University of Bristol.
Brooke E. Flammang is an American biologist at the New Jersey Institute of Technology. She specializes in functional morphology, biomechanics, and bioinspired technology of fishes. Flammang is a discoverer of the radialis muscle in shark tails. She also studies the adhesive disc of the remora, and the walking cavefish, Cryptotora thamicola. Her work has been profiled by major news outlets including The New York Times, The Washington Post, Wired, BBC Radio 5, Discovery Channel, and National Geographic Wild. She was named one of the "best shark scientists to follow" by Scientific American in 2014.
Sharlene E. Santana is a Venezuelan–American biologist, currently serving as the Curator of Mammals at the Burke Museum of Natural History and as a professor of Evolutionary biology at the University of Washington, in Seattle, Washington. Her research primarily focuses on the order Chiroptera (bats), and her work often engages with a diverse range of biological disciplines, including evolution, systematics, biomechanics, behavioral studies, and ecology. Santana has worked to expand opportunities for underrepresented minorities in STEM fields and has relied on innovative applications of technology to increase the amount of high-quality scientific information that is available to the general public.
Martha M. Muñoz is an American evolutionary biologist and an Assistant Professor of Ecology and Evolutionary Biology at Yale University. She is also an assistant curator for the Division of Vertebrate Zoology at the Yale Peabody Museum. In particular, Muñoz researches the influence of biomechanics and behavior on evolution in reptiles, amphibians, and fishes. In 2024, she was named a MacArthur Fellow.
