Question

Pristis belongs to the class of ___________
A. Elasmobranchii
B. Holocephali
C. Dipnoi
D. Teleostomi

Answer 1

Hint: Pristis (sawfish) is a saw-shaped head with healthy teeth at the edges. He used his teeth to attack and defend. His body is a cross between a shark and a stingray. There are no ventral or anal fins. The Pristis is ovoviviparous.

Complete answer:
-Elasmobranchii-The Elasmobranchii includes a group of fish known as sharks and rays. Members of this class are also known as Elasmobranchs, which means gill-lamellae fish. Despite the large morphological differences, they form a very dense group and are characterized by the following diagnostic features: The body is covered with small cutaneous plasma scales (teeth) and hard skin containing mucous glands. The mouth is on top. Dental fever (special placoid scales) in the mouth. The skeleton has cartilaginous properties, but the bone formation of the spine has been reported in small dogs (Scyliorhinus canaliculi). There can be one or two nostrils, but they do not open in the mouth. It has a middle and double fin. The pelvic fin (male) is equipped with a clip. The fins hold on to the flippers. The caudal fin is mostly heterogeneous. This class includes cartilaginous fish, including the shark and the rays, skates, and sawfish (superorder Batoidea)
-Holocephali -Lund uses the term bradyodontic rather than holocephalic. There are about thirty species.
General characteristics: The body of an adult is quite hard and naked. There are five branchial arches. The four-gill openings are protected by one fleshy gill sheath. The bone plate is on the jaw, not on the teeth that crushed it. The excretory cavity disappears. The skull is made in a holographic style. There is no bone (cartilage) in the skeleton. Pectoral fin wide, leaf-shaped Maxillary cartilage fuses with cranial nerves (base of the skull), name symbol, square tent Additional braces with unknown features on a person's head are called head restraints. The tail is thin, like a whip.
-Dipnoi-Dipnoan or lungfish of this class. The location of the biplane between the fish is important. They represent something of a transitional group between calves and amphibians.
General characteristics: External branchial foramen, covered by a single and branchial cover. Specific grinding of teeth, mainly in the palate. Absence of joints supporting the teeth of the upper and upper jaw. There is an inner opening in the mouth. Air bubbles like lungs with special low blood circulation. The self-proclaimed skull (rectangular tent fused with an indivisible skull). Middle fins merge with the posterior third of the body. The meninges and spine harden a little.
-Teleostomi- Members of the class are highly evolved forms among fish. They have many diagnostic functions that differentiate them from other fish species.
General characteristics: The body is covered with thin cycloid skin, ctenoid or ganoid scales. There are teeth at the end of the mouth. The external branchial opening is closed with a reinforced cover. Chin suspension is usually Hyostyl. There is usually any form of air bubbles that sometimes act like lungs. The heart is biogenic (holes and chambers of the heart) with venous sinuses and cones.
So, from the above points it's clear that the correct option is Elasmobranchii.

Hence, the correct answer is option (A).

Note: Elasmobranchs (sharks and rays) and rats (chimaeras) are pyrogenic aquatic animals, but in Lamnidae (mackerel-sharks-Carcharodon, Lamna and Isurus) they are partially warm-blooded and have a modified circulatory system that can store body heat. The temperature of the aquatic environment. The genus Elasmobranchii includes live gnathostomes. The classification of the Elasmobranchii class is still unsatisfactory due to the lack of complete fossils and an intermediate stage.