Which are examples of amniotes?
SynapsidSauropsidaCatDogDinosaurSnakeAmniote/Lower classifications
What are the two main groups of amniotes?
There are two main divisions of amniotes, the sauropsid amniotes and the synapsid amniotes. The sauropsid amniotes include the reptiles and birds. Formally, this constitutes many different groups, but the sauropsid amniotes share many derived characteristics which separate them from the synapsids.
Which is an Amniote?
Amniotes include terrestrial vertebrates that lay amniotic eggs. They include reptiles, birds (which are a specific type of reptile), and mammals.
Which of the following group of animals belongs to amniotes?
So, the correct option is 'Birds, reptiles and mammals'.
Which is not an amniote?
Answer and Explanation: The animal that is NOT an amniote is A) bullfrog. Amniotes are vertebrates that are within an amnion during embryonic or fetal development. Mammals (e.g. humans), reptiles (e.g. coral snake), and birds (e.g. bald eagle) are amniotes.
What are amniotes and non amniotes?
Amniotes are higher vertebrates who have an amnion during their embryonic stage. Anamniotes are lower vertebrates who do not have an amnion during their embryonic stage. Vertebrate Classification. Amniotes are higher vertebrates.
What makes an organism an amniote?
Amniotes are characterized by having an egg equipped with an amnion, an adaptation to lay eggs on land or retain the fertilized egg within the mother. Amniote embryos, whether laid as eggs or carried by the female, are protected and aided by several extensive membranes.
What are three amniotes lineages?
The first amniote fossils, Archaeothyris (a synapsid), Hylonomus (a reptile), and Paleothyris (a reptile; Fig.
Are mammals amniotes?
Amniotes comprise all fully terrestrial vertebrates and include extant squamates, turtles, crocodiles, birds and mammals. The origin of amniotes, tightly linked to the amniotic egg as a key innovation, represents a major transition in the evolutionary history of tetrapods.
What are the amniotes and its types?
SynapsidSauropsidaCatDogDinosaurSnakeAmniote/Lower classificationsAmniotes are a clade of tetrapod vertebrates that comprise sauropsids (including reptiles and birds) and synapsids (including non-mammalian synapsids and mammals).
Which group of vertebrates are not amniotes?
The anamniotes are an informal group comprising the fishes and the amphibians which lay their eggs in water. They are distinguished from the amniotes (reptiles, birds and mammals), which lay their eggs on land or retain the fertilized egg within the mother.
Why reptiles are called first amniotes?
Reptile hatching from an egg The first reptiles produced leathery amniotic eggs that could be laid on land. Reptiles were the first amniotes.
What are amniotes and its types?
SynapsidSauropsidaCatDogDinosaurSnakeAmniote/Lower classifications
Why reptiles are called first amniotes?
Reptile hatching from an egg The first reptiles produced leathery amniotic eggs that could be laid on land. Reptiles were the first amniotes.
Why are mammals considered amniotes?
Amniotes are a clade of tetrapod vertebrates comprising the reptiles, birds, and mammals. Amniotes are characterized by having an egg equipped with an amnion, an adaptation to lay eggs on land or retain the fertilized egg within the mother.
Are amphibians amniotes?
The amniotes, reptiles, birds, and mammals, are distinguished from amphibians by their terrestrially-adapted egg, which is protected by amniotic membranes.
What are the two groups of eggs that are unique to the Amniotes?
This kind of egg is unique to the amniotes, a group that includes two large clades: Synapsida (mammals and their relatives) and Diapsida (reptiles, dinosaurs, and birds). Amniota also includes a few odd groups, like turtles, whose relationships are murky.
Why is the embryo still surrounded by amniotic fluid?
The embryo is still surrounded by an amnion filled with amniotic fluid; because it is next to and surrounds the embryo, doctors will sometimes examine the fluid to determine the health of the unborn child.
What is the name of the sac that connects the uterus to the fetus?
The allantois and yolk sac become the umbilical cord, providing a connection through which food reaches the fetus, and wastes are removed. Together with part of the chorion, these membranes make up the placenta, which physically attaches the embryo to the uterine wall of its mother.
What is the role of the allantois in the development of an embryo?
The allantois performs two very important functions for the embryo, providing for gas diffusion, and removal of wastes. Food for the developing embryo comes from the yolk sac, which reduces in size as the embryo matures. Surrounding all the other membranes is the chorion, providing an overall enclosure for the young.
What are the membranes that protect the embryo?
Inside the egg are a series of fluid-filled membranes which permit the embryo to survive: the amnion, allantois, yolk sac, and chorion. Surrounding and protecting the embryo is the amnion, filled with amniotic fluid, and providing the embryo with a stable fluid environment.
Do mammals lay eggs?
Perhaps seeing mammals on this list surprised you since most mammals do not lay eggs, but the earliest mammals did lay eggs, and a few, such as the monotremes, still do. To understand this, you must first understand the structure of the amniote egg.
How do amniotes get their name?
The Amniota derives its name from the amniotic egg, a synapomorphy shared by all members (Fig. 1.12 and Fig. 1.13). Other stem amniotes may have had amniotic eggs, although they are not classified as amniotes. A fossil taxon cannot be identified as an amniote or anamniote by structure of its egg, because few fossil eggs of anthracosaurs have been found. Further, no eggs have been found in association with an adult’s skeleton or with a fossil embryo showing extra-embryonic membranes. Bony traits must be used to determine which taxa are amniotes and which ones are not, and there is no unanimity in which bony traits define an amniote. Indeed, amniotes are commonly defined by content; for example, Amniota comprise the most recent common ancestor of mammals and reptiles and all of its descendants.
Where did the first amniotes come from?
The first amniote fossils, Archaeothyris (a synapsid), Hylonomus (a reptile), and Paleothyris (a reptile; Fig. 1.12 ), are from the Middle Pennsylvanian, but they are not primitive amniotes in the sense of displaying numerous transitional traits. Divergence of synapsids and reptilian stocks was already evident.
How is an amniote diagnosed?
Amniota is diagnosed by a suite of characters, including presence of an amniote egg (see below), caniniform teeth, two or more vertebrae in contact with the pelvic girdle, internal fertilization, and keratin (a protein that acts as the building block for scales, nails, hooves, hair, and feathers).
What are the bones that border the fenestra?
The pattern of fenestration is defined by the typical configuration of bones that border the fenestra. The typical configurations of bones for the skull types are illustrated in Figure 1.9. In the synapsid condition the dorsal border of the fenestra is formed mainly by the squamosal and postorbital bones, although the parietal may occasionally participate, whereas the ventral border is formed mainly by the squamosal and jugal bones, with the quadratojugal bone occasionally contributing. The infratemporal fenestra of the diapsid skull is bordered by the jugal, squamosal, and postorbital bones, with the quadratojugal occasionally participating. The supratemporal fenestra is bordered by the postorbital, squamosal, parietal, and, in many cases, the postfrontal bones. Two bony bars, temporal bars (or arcades), are clearly defined in the diapsid skull, a ventral bar formed mainly by the jugal and quadratojugal bones, and a dorsal bar, between the fenestrae, formed by the postorbital and squamosal bones. The fenestra of euryapsid skulls is bordered usually by the parietal, postfrontal, postorbital, and squamosal bones, with the last two meeting ventrally below the fenestra. From these basic patterns, several specializations have evolved, as discussed later.
Where did amniotes first appear?
Amniotes first arose in the milieu of coal swamp forests that give the Carboniferous Period its name. The amniote reproductive strategy of laying eggs with embryos producing extra-embryonic membranes allowed amniotes to eschew reproduction in ponds and streams (as seen in most modern amphibians) and undertake a direct form of development firmly on land. Modern phylogenetic studies on amniote interrelationships broadly agree that synapsids and reptiles are sister taxa within Amniota. Both groups diversified from their first appearances in lycopod tree stumps at Joggins, Nova Scotia, c. 314 Ma, giving rise to diverse assemblages of insectivores, small- to large-bodied carnivores, and high-fiber herbivores by the end of the Carboniferous. The succeeding Permian Period records increasing diversity of amniotes, and for the first time in their evolutionary history the first fully aquatic amniotes, and the first facultatively bipedal amniotes make their appearance. Many Permo-Carboniferous groups exhibit increasing body size until their final appearances at the end of the early Permian or later during the period.
Which period recorded the first fully aquatic amniotes?
The succeeding Permian Period records increasing diversity of amniotes, and for the first time in their evolutionary history the first fully aquatic amniotes, and the first facultatively bipedal amniotes make their appearance.
Which bones are involved in the dorsal border of the fenestra?
In the synapsid condition the dorsal border of the fenestra is formed mainly by the squamosal and postorbital bones , although the parietal may occasionally participate, whereas the ventral border is formed mainly by the squamosal and jugal bones, with the quadratojugal bone occasionally contributing.
What is the most recent common ancestor of all living amniotes and all their descendants?
Note: the present page is concerned with the Crown Group Amniotes, that is, the most recent common ancestor of all living amniotes and all their descendants. It is very likely however that there were reptiles, that is, amniotes, existing before then, and even that some of these are already known from the fossil record. The problem is, it is very difficult to know exactly where amongst the various transitional forms between the amphian and reptilian condition reviewed in the previous pages the ability lay eggs on dry land first appeared. But the distinction on this page is not the physiological or evolutionary between pre-amniotes and amniotes, but the phylogenetic (family history of life) distinction between the first amniotes (and associated non-amniotes) and one particular group of later (though still very early and primitive) amniotes (reptiles) that became the ancestors of all later reptiles as well as mammals and birds. MAK111121
Who wrote the book Diversification of the Amniotes?
Gauthier, J. A. 1994. The diversification of the amniotes. In D. R. Prothero and R. M. Schoch (ed.) Major Features of Vertebrate Evolution: 129-159. Knoxville: The Paleontological Society.
Is there a relationship between birds and mammals?
Initially, some gene sequences suggested a close relationship between birds and mammals, although never with strong statistical support (e.g., Bishop & Friday, 1987; Goodman et al., 1987; Hedges et al., 1990). More recently, a study of the molecular evidence for the origin of birds (15 genes; 5280 nucleotides, 1461 amino acids) discovered strong support (100% bootstrap P value, BP) for a close relationship between birds and crocodilians (Hedges, 1994). A smaller data set of 11 transfer RNA genes (686 sites) also resulted in a bird-crocodilian grouping (Kumazawa & Nishida, 1995). A basal position for mammals was supported (99% BP) by analysis of a 3 kilobase portion of the mitochondrial genome containing the two ribosomal RNA genes (Hedges, 1994). In the same study, a Sphenodon-squamate relationship also was found, but support for that grouping and for the position of turtles was not very strong.
Do amniotes have extinct taxa?
The three trees presented above include only extant taxa , and many phylogenetic analyses of amniotes have ignored extinct taxa. However, it is important to bear in mind that discovering the globally most parsimonious tree requires the inclusion of extinct taxa in a phylogenetic analysis (Gauthier et al., 1988b). Without fossils, the best-supported tree for amniotes inferred from morphological data is the following (although only one more step is required to switch the positions of lepidosaurs and turtles):
What is the amniote egg?
Many amniote synapomorphies are widely interpreted as adaptations to the rigors of life on land. Indeed, Amniota owes its name to what may be its most distinctive attribute, a large "amniotic" egg. While most of us are most familiar with the hard-shelled eggs found in birds, Stewart (1997) showed that the first amniotic eggs probably had a flexible outer membrane, and that a mineralized (but still flexible) outer membrane is a synapomorphy of reptiles. The heavily mineralized, hard shell is a synapomorphy of archosaurs (crocodiles and birds), and it also appeared at least three times in turtles, and a few times in squamates. This probably explains why the oldest known amniotic egg (Coyne, 1999) only dates from the Lower Triassic (220 My), whereas the oldest amniote dates from the Upper Carboniferous (310 My); the eggs of most (if not all) Paleozoic amniotes must have had a flexible, poorly mineralized or unmineralized outer membrane, and thus had a low fossilization potential (Laurin, Reisz & Girondot, 2000).
Where did the amniotes originate?
The oldest amniotes currently known date from the Middle Pennsylvanian locality known as Joggins, in Nova Scotia (Carroll, 1964). The relationships of these fossils indicate that amniotes first diverged into two lines, one line (Synapsida) that culminated in living mammals, and another line (Sauropsida) that embraces all the living reptiles (including birds). One Joggins fossil, the "protorothyridid" Hylonomus, appears to be a very early member of the line leading to Sauria (Crown-clade diapsids), the clade encompassing all living diapsids. This suggests that the more inclusive clade of which turtles (Testudines) are part (Anapsida) in most morphological phylogenies had diverged as well, even though its current record extends back only to the Lower Permian (Laurin & Reisz, 1995).
Is an amniote a close relative of an amniote?
However, more recent studies suggested that it was only a close relative of amniotes (Smith son et al., 1994), and the latest study even suggested that it was more likely to be a stem-tetrapod or an early amphibian than a relative of amniotes (Laurin & Reisz, 1999).
Do amniotes have sacral ribs?
For example, amniotes have at least two pairs of sacral ribs, instead of just one pair. They also have an astragalus bone in the ankle, instead of separate tibiale, intermedium, and proximal centrale bones. Finally, they have paired spinal accessory (11th) and hypoglossal (12th) cranial nerves incorporated into the skull, in addition to the ten pairs of cranial nerves present in amphibians.
Do amniotes have extinct taxa?
The three trees presented above include only extant taxa , and many phylogenetic analyses of amniotes have ignored extinct taxa. However, it is important to bear in mind that discovering the globally most parsimonious tree requires the inclusion of extinct taxa in a phylogenetic analysis (Gauthier et al., 1988b). Without fossils, the best-supported tree for amniotes inferred from morphological data is the following (although only one more step is required to switch the positions of lepidosaurs and turtles):
Is there a relationship between birds and mammals?
Initially, some gene sequences suggested a close relationship between birds and mammals, although never with strong statistical support (e.g., Bishop & Friday, 1987; Goodman et al., 1987; Hedges et al., 1990). More recently, a study of the molecular evidence for the origin of birds (15 genes; 5280 nucleotides, 1461 amino acids) discovered strong support (100% bootstrap P value, BP) for a close relationship between birds and crocodilians (Hedges, 1994). A smaller data set of 11 transfer RNA genes (686 sites) also resulted in a bird-crocodilian grouping (Kumazawa & Nishida, 1995). A basal position for mammals was supported (99% BP) by analysis of a 3 kilobase portion of the mitochondrial genome containing the two ribosomal RNA genes (Hedges, 1994). In the same study, a Sphenodon -squamate relationship also was found, but support for that grouping and for the position of turtles was not very strong.
Who wrote the book Diversification of the Amniotes?
Gauthier, J. A. 1994. The diversification of the amniotes. In D. R. Prothero and R. M. Schoch (ed.) Major Features of Vertebrate Evolution: 129-159. Knoxville: The Paleontological Society.
What is anamniote classification?
The features unifying the anamniotes was first noted by Thomas Henry Huxley in 1863, who coined the phrase Ichtioid or Ichthyopsida ("fish-face") for the group. It is a taxonomic classification just below the level of Vertebrata, though Huxley presented the Ichthyopsida as an informal unit and never ventured to forward a Linnaean rank for the group. The term ichthyopsida means fish-face or fish-like as opposed to the sauropsida or lizard-face animals ( reptiles and birds) and the mammals. The group representing an evolutionary grade rather than a clade, the term anamniote is now used as an informal way of denoting the physical property of the group, rather than as a systematic unit.
What is the amnion in an egg?
The name refers to the amnion, an embryonic membrane produced during the fetal development of amniotes which serves to transport oxygen into the egg and expel carbon dioxide. As the name suggests, anamniotes do not develop an amnion during fetal life and are able to exchange oxygen, carbon dioxide and waste metabolites with the surrounding water.
What are the characteristics of anamniotes?
The group is characterized by retaining the primitive vertebrate condition in several traits: Absence of an amnion. Absence or rudimentary condition of the allantois. Nucleated red blood cells. Permeable skin allowing diffusion of water and gases directly through the skin.