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All vertebrate jaws, including the human jaw, evolved from early fish jaws. The appearance of the early vertebrate jaw has been described as "perhaps the most profound and radical evolutionary step in the vertebrate history". [4] [5] Fish without jaws had more difficulty surviving than fish with jaws, and most jawless fish became extinct.
Bite force quotient (BFQ) is a numerical value commonly used to represent the bite force of an animal adjusted for its body mass, while also taking factors like the allometry effects. The BFQ is calculated as the regression of the quotient of an animal's bite force in newtons divided by its body mass in kilograms. [ 1 ]
[3] [9] [10] Jaw development in vertebrates is likely a product of the supporting gill arches. This development would help push water into the mouth by the movement of the jaw, so that it would pass over the gills for gas exchange. The repetitive use of the newly formed jaw bones would eventually lead to the ability to bite in some gnathostomes ...
Within the chondrichthyans, horn sharks (Heterodontidae), some rays (Myliobatidae) and chimeras (Holocephali) exhibit durophagous behaviour. They have adaptations to allow for this including stout flattened teeth, hypertrophied jaw adductor muscles and robust jaws to feed on hard prey such as crustaceans and molluscs.
Although sharks rarely bite humans, the tiger shark is reported to be responsible for a large share of fatal shark-bite incidents, and is regarded as one of the most dangerous shark species. [61] [62] They often visit shallow reefs, harbors, and canals, creating the potential for encounter with humans. [5]
This is an accepted version of this page This is the latest accepted revision, reviewed on 12 December 2024. Extinct genus of saber-toothed cat Smilodon Temporal range: Early Pleistocene to Early Holocene, 2.5–0.01 Ma Pre๊ ๊ O S D C P T J K Pg N ↓ Mounted S. populator skeleton at Tellus Science Museum Scientific classification Domain: Eukaryota Kingdom: Animalia Phylum: Chordata Class ...
Shark teeth are strong and made of enamel. Many sharks have 3 rows of teeth. These teeth are embedded in the gums, not the jaw. [10] Sharks are born with teeth that are constantly being replaced. Teeth are replaced every two weeks, approximately. [10] The shape of the teeth determine the diet of the shark.
In taxonomy, shark teeth are counted as follows: rows of teeth are counted along the line of the jaw, while series of teeth are counted from the front of the jaw inward. [19] A single tooth row includes one or more functional teeth at the front of the jaw, and multiple replacement teeth behind this. [ 20 ]