What are the characteristics of Gnathostomata?
Gnathostomes are characterized by:
- A vertically biting device called jaws, and which is primitively made up by two endoskeletal elements, the palatoquadrate and Meckelian cartilage, and a number of dermal elements called teeth, sometimes attached to large dermal bones.
- Pelvic fins.
What are the three gnathostomes?
Classification. The group, Gnathostomata, is traditionally a superclass, broken into three top-level groupings: Chondrichthyes, or the cartilaginous fish; Placodermi, an extinct clade of armored fish; and Teleostomi, which includes the familiar classes of bony fish, birds, mammals, reptiles, and amphibians.
What are the classes of Gnathostomata?
Gnathostomata A subphylum or superclass of chordates consisting of all vertebrates that possess jaws. It contains six extant classes: Chondrichthyes (cartilaginous fishes), Osteichthyes (bony fishes), Amphibia, Reptilia, Aves (birds), and Mammalia. Compare Agnatha.
Why fishes are considered among Gnathostomata?
Gnathostomes or “jaw-mouths” are vertebrates that possess jaws. Early gnathostomes were jawed fishes that possessed two sets of paired fins, which increased their ability to maneuver accurately. These paired fins were pectoral fins, located on the anterior body, and pelvic fins, on the posterior.
What do you mean by Gnathostomata?
: a superclass or other division of Vertebrata comprising those with jaws — compare agnatha.
What class are tetrapods?
Amphibia
Tetrapod, (superclass Tetrapoda), a superclass of animals that includes all limbed vertebrates (backboned animals) constituting the classes Amphibia (amphibians), Reptilia (reptiles), Aves (birds), Mammalia (mammals), and their direct ancestors that emerged roughly 397 million years ago during the Devonian Period.
Are birds Gnathostomata?
Gnathostomes or “jaw-mouths” are vertebrates that possess jaws. Gnathostomes later evolved into all tetrapods (animals with four limbs) including amphibians, birds, and mammals. Early gnathostomes were jawed fishes that possessed two sets of paired fins, which increased their ability to maneuver accurately.
Is a lamprey a Gnathostome?
Lampreys are jawless fishes (or agnathans), closely related to other living vertebrates, the jawed vertebrates (or gnathostomes). They, along with hagfish, are the only known surviving lineage of once diverse groups of jawless fishes.
Are humans Gnathostomata?
Jawed vertebrates (gnathostomes) comprise more than 99% of living vertebrate species, including humans.
Are all fish tetrapods?
In a strict evolutionary sense, all tetrapods are essentially “limbed fish,” because their ultimate vertebrate ancestor is a fish. All tetrapods share a variety of morphological features.
Which is common to all tetrapods?
Tetrapods are a group of vertebrates that includes amphibians, reptiles, birds, and mammals. One of the key characteristics of tetrapods is that they have four limbs or, if they lack four limbs, their ancestors had four limbs.
What kind of vertebrates are in the Gnathostomata?
The Gnathostomes. Extant Gnathostomata, the clade that includes all jawed vertebrates, including the tetrapods (terrestial vertebrates), divides into the Chondrichthyes – catiligenous fish, sharks, rays, and chimaeras – and the Osteichthyes (vony fish).
What kind of teeth does a gnathostome have?
In addition to opposing jaws, living gnathostomes have teeth, paired appendages, and a horizontal semicircular canal of the inner ear, along with physiological and cellular anatomical characters such as the myelin sheaths of neurons.
Where does the Gnathostomata end in a lamprey?
Gnathostomata: This duct either leads posteriorly to the pharynx, as in hagfish and galeaspids, or ends as a blind pouch, as in lampreys and osteostracans. In gnathostomes, the duct or pouch forms a thin buccohypophysial canal in the palate, while the nasal sacs open separately to the exterior by external nares.
How are tetrapods related to coelacanth and lungfish?
The origin of tetrapods is a major outstanding issue in vertebrate phylogeny. Each of the three possible principal hypotheses (coelacanth, lungfish, or neither being the sister group of tetrapods) has found support in different sets of data.
