Do sharks have palatoquadrate?
In sharks and rays, the upper jaw (the palatoquadrate cartilage) is not fused to the chondrocranium, but rather articulates with it. In amphistyly (Hexanchiformes), the palatoquadrate has a postorbital articulation and also an articulation in the orbital region.
Do sharks have a splanchnocranium?
The shark has a chondrocranium and splanchnocranium but no dermatocranium. Its skeleton is also cartilaginous as opposed to being made of bone.
What does the palatoquadrate do?
the primary upper jaw in gnathostomatous vertebrate animals and man. In cartilaginous fish and in the larvae of amphibians, the palatoquadrate cartilage functions as a jaw; in bony fish, terrestrial vertebrates, and man, it becomes part of the palate with the development of secondary jaws.
What are the derivatives of the palatoquadrate?
The first branchial arch of mice is the largest and has two major components: the maxillary and mandibular branch derivatives of the palatoquadrate cartilage (PQ) and Meckel’s cartilage (MC), respectively. In mice, the PQ derivatives are the ala temporalis and the incus (but see Zeller, 1987.
Do sharks have a Chondrocranium?
In the Elasmobranchs (sharks and rays) it is composed of cartilage (chondrocranium), but in most other vertebrates, the cartilage is replaced by bone (endochondral or replacement bone). Note that these bones are endochondral (or replacement or nondermal) bones.
Which of the following is a part of splanchnocranium?
The splanchnocranium consists of cartilage and endochondral bone. In mammals, the splanchnocranium comprises the three ear ossicles (i.e., incus, malleus, and stapes), as well as the alisphenoid, the styloid process, the hyoid apparatus, and the thyroid cartilage.
What is Neurocranium and Dermatocranium?
The neurocranium/chondrocranium includes the box that encloses the brain and the capsules surrounding the sense organs. It protects the brain. 2. The splanchnocranium is the visceral portion of the skull that supports the gills and contributes to the jaws. 3.The dermatocranium is the dermal bone that is believed to.
What animals have quadrate Fusion?
The quadrate bone is a skull bone in most tetrapods, including amphibians, sauropsids (reptiles, birds), and early synapsids. In most tetrapods, the quadrate bone connects to the quadratojugal and squamosal bones in the skull, and forms upper part of the jaw joint.
What is the chondrocranium of a shark?
The chondrocranium is the large single element of the head skeleton (Figure 3.2). It surrounds and provides support for the brain and sense organs. The scoop-like rostrum projects anteriorly and contains the precerebral cavity.
What articulates with the palatoquadrate of a shark?
In hyostyly (galeomorph sharks), the palatoquadrate articulates with the ethmoid (preorbital) region of the chondrocranium. In euhyostyly (batoids), an anterior articulation is lacking and the hyomandibula supplies the only articulation between the chondrocranium and palatoquadrate.
What is the palatoquadrate attached to?
Early sharks and bony fish (now almost all extinct, except for the extant six-gilled shark) had the palatoquadrate attached by ligaments to the chondrocranium. In addition, the hyoid arch specialized to form the hyomandibular, which helped to stabilize the posterior end of the jaws and was attached by a second ligament.
What is the splanchnocranium?
Splanchnocranium comes from neural crest cells and is either cartilage or replacement bone. Arch 1 forms the jaws and is called the mandibular arch. We will particularily study the articular which becomes the malleus of the ear in mammals and the quadrate which forms the incus.
Is the upper jaw fused to the chondrocranium?
In sharks and rays, the upper jaw (the palatoquadrate cartilage) is not fused to the chondrocranium, but rather articulates with it. The posterior articulation is mediated by the hyomandibula, the dorsal element of the first gill arch posterior to the jaws, that connects the jaw joint with the chondrocranium.