Dorsal Ribs

Dorsal Ribs

 

a pair of thin bones in teleosts. The dorsal ribs are located in the myocommata—the connective-tissue layers between the muscle segments, or myomeres. They are attached to the neural arch, to the body of a vertebra, or to another rib. The dorsal ribs develop indirectly from the connective tissue and serve a supportive function. Some of the myomere fibers are attached to the dorsal ribs.

In fish of the families Cyprinidae and Clupeidae, each myomere has several pairs of dorsal ribs. As a result, the flesh of these fishes is particularly bony.

References in periodicals archive ?
Referred material: CAMSM J29960, CAMSM J29961, CAMSM J29964, CAMSM J29965, several fragments of costal plates and of the free region of the dorsal ribs, all of them from the type locality and horizon (Fig.
Emended diagnosis: Basal member of Eucryptodira, more than 60 cm in length, possessing well-developed free regions of the dorsal ribs, which correspond to more than three quarters of the width of the last pair of costals, and sharing the following character combination: absence of nuchal notch; presence of a single cervical scute; very wide vertebral scutes; wide fontanelles between the costal and the peripheral plates; robust and high plastral processes; angle formed by the scapular and the acromial processes of the scapula around 110 degrees.
However, it differs from Thalassemys due to numerous characters, including: the presence of very wide fontanelles between the costal and peripheral plates, with the free region of the dorsal ribs being very wide relative to the width of these plates, especially the last pairs of costals; absence of the carapace cordiform morphology characteristic of Thalassemys; very wide vertebral scutes; different morphology of the preserved suprapygal; much robust and higher plastral buttresses.
The great development of the free region of the dorsal ribs observed in the taxon from Ely, together with the reduction in width of the other region of the costal plates, differs from the condition present in the taxon from the Oleron Island, Hylaeochelys and Plesiochelyidae.
4Q-X), coming from the type locality and horizon of this taxon, are elements of the carapace, in which the presence of the very long free regions of the dorsal ribs that characterize Enaliochelys chelonia is recognized.
Comments: In the original diagnosis, Ruiz-Omenaca (2011) provided the following autapomorphies for Delapparentia turolensis: 1) posterior dorsal ribs with long, parallel and unfused capitulum and tuberculum, 2) ossified sternal ribs, and 3) horizontal, twisted and lateromedially expanded preacetabular process of ilium (convergent in Zalmoxes), as well as the presence of anterior dorsal ribs with a pneumatic foramen and an ischium that is large in relation to the ilium.
a partial postcranial skeleton that comprises the neural arch of the axis and another four cervical vertebrae, one centrum and some fragments of neural arches of dorsal vertebrae, three vertebral centra and some fragments of neural spines of sacral vertebrae, nine anterior caudal vertebrae, cervical and dorsal rib fragments, five haemal arches, ossified tendon fragments, a proximal fragment of the right scapula and the incomplete left pelvic girdle represented by the anterior and dorsal part of the ilium, prepubis and a proximal fragment of the ischium (Figs.
Material: A partial skeleton composed at least by four dorsal vertebrae (MPA D-318/319/324/332), ten dorsal ribs (MPA D-320/322/323/330/333/335/337/338/344/34 8), fragments of caudal centra (uncatalogued), and a fragmentary femur (MPA D-317).