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 ?
The dorsal ribs are slender, and separated from the articular facets of the vertebrae with which they articulated.
Abbreviations: cor, coracoid; cr, cervical rib; cv, cervical vertebra; dc-1 to 3, distal carpals; dr, dorsal rib; dsc, dorsal process of scapula; dt-1and 2, distal tarsals; dv, dorsal vertebra; fe, femur; fi, fibula; fib, fibulare; glc, glenoid cavity; h, humerus; int, intermedium; mc-1 to 3, metacarpals; mt-1 to 4, metatarsals; naf, facet for neural arch; pu, pubis; pv, pectoral vertebra; rd, radius; rdl, radiale; rf, facet for rib; sc, scapula; ti, tibia; tib, tibiale; ul, ulna; uln, ulnare; vsc, ventral process of scapula.
PCL is large, slightly narrower than the cell body depth, and it is as long as the cell body or even longer, supported by straight or sigmoid vertical (including 2 dorsal ribs) and horizontal ribs, forming a sort of subquadrangular chamber; horizontal ribs support PCL near its anterior margin.
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.
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.
The large size of the Delapparentia holotype may be due to the senile state of the individual, which is also suggested by the fusion of certain axial elements (dorsal ribs and neural arches, pairs of caudal centra) and the ossification of the sternal ribs.
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).
Dorsal ribs.- The ribs are slender elements provided of a long shaft, a reduced tuberculum and a well developed neck ending in a long capitulum (Figs.