Callorhinchidae
Chimaeras are cartilaginous fish in the order Chimaeriformes , known informally as ghost sharks, rat fish, spookfish, or rabbit fish; the last three names are not to be confused with rattails, Opisthoproctidae, or Siganidae, respectively.
...
shark
Sharks are a group of elasmobranch fish characterized by a cartilaginous skeleton, five to seven gill slits on the sides of the head, and pectoral fins that are not fused to the head. Modern sharks are classified within the clade Selachimo ...
s and
rays
Ray may refer to:
Fish
* Ray (fish), any cartilaginous fish of the superorder Batoidea
* Ray (fish fin anatomy), a bony or horny spine on a fin
Science and mathematics
* Ray (geometry), half of a line proceeding from an initial point
* Ray (gra ...
Lower Cretaceous
Lower may refer to:
*Lower (surname)
*Lower Township, New Jersey
*Lower Receiver (firearms)
*Lower Wick
Lower Wick is a small hamlet located in the county of Gloucestershire, England. It is situated about five miles south west of Dursley, eig ...
and vanished in the
Pliocene
The Pliocene ( ; also Pleiocene) is the epoch in the geologic time scale that extends from 5.333 million to 2.58 It was most prominent during the Late
Cretaceous
The Cretaceous ( ) is a geological period that lasted from about 145 to 66 million years ago (Mya). It is the third and final period of the Mesozoic Era, as well as the longest. At around 79 million years, it is the longest geological period of th ...
. Many ''Edaphodon'' species were found in the Northern Hemisphere, but species from the Southern Hemisphere are also known (e.g., ''E. kawai'' from
New Zealand
New Zealand ( mi, Aotearoa ) is an island country in the southwestern Pacific Ocean. It consists of two main landmasses—the North Island () and the South Island ()—and over 700 smaller islands. It is the sixth-largest island count ...
and ''E. snowhillensis'' from
Antarctica
Antarctica () is Earth's southernmost and least-populated continent. Situated almost entirely south of the Antarctic Circle and surrounded by the Southern Ocean, it contains the geographic South Pole. Antarctica is the fifth-largest contine ...
).
Description
Like most other chimaeriforms, ''Edaphodon'' is known mainly from poorly preserved specimens because its skeleton was made of
cartilage
Cartilage is a resilient and smooth type of connective tissue. In tetrapods, it covers and protects the ends of long bones at the joints as articular cartilage, and is a structural component of many body parts including the rib cage, the neck an ...
. So, in most cases, only tooth plates and fin spines have been preserved, and they are also often dissociated. Like other chimaeriforms, it fed using six pairs of tooth plates—one pair on the lower jaw (mandibular) and two pairs on the upper (vomerine and palatine), which bear tooth-like hypermineralized areas known as tritors. The patterning of the tritors is used to distinguish chimaeriforms. In ''Edaphodon'', the vomerine tooth plates are covered in rod-like tritors; each palatine tooth plate is massive, and has one large tritor on the outer edge and two large tritor pads and one small tritor pad in the middle; and each mandibular tooth plate is massive and has a beak-like tritor at the front end, along with two pairs of tritor pads at their outer edges and a single large tritor pad in the middle.
The closest relative of ''Edaphodon'' was ''Ischyodus''. They were generally similar, but ''Ischyodus'' had four large tritor pads on its palatine tooth plates, as well as thinner mandibular tooth plates with shorter beaks. ''Edaphodon'' would have used its tritors for both crushing hard-shelled and slicing other prey such as fishes, sharks, and marine reptiles. In the
Upper Cretaceous
The Late Cretaceous (100.5–66 Ma) is the younger of two epochs into which the Cretaceous Period is divided in the geologic time scale. Rock strata from this epoch form the Upper Cretaceous Series. The Cretaceous is named after ''creta'', the ...
of Alabama, where ''I. bifurcatus'', ''E. barberi'', and ''E. mirificus'' coexisted, the two genera may have had different diets, with ''Ischyodus'' feeding on more hard-shelled prey.
Externally, ''Edaphodon'' would have been similar to other rabbitfish in appearance. However, at least some species of ''Edaphodon'' would have been far larger. The largest mandibular tooth plates of the living ''
Callorhinchus
''Callorhinchus'', the plough-nosed chimaeras or elephantfish, are the only living genus in the family Callorhinchidae (sometimes spelled Callorhynchidae). A few extinct genera only known from fossil remains are recognized. ''Callorhinchus'' spp ...
'' measure in length; the largest ''E. sedgwickii'' mandibular tooth plates reach , and ''E. snowhillensis'' mandibular tooth plates also reached . Based on palatine tooth plates, the species ''E. barberi'', ''E. mirificus'', and ''E. snowhillensis'' have been estimated at over in length, with one individual of ''E. mirificus'' reaching .
type species
In zoological nomenclature, a type species (''species typica'') is the species name with which the name of a genus or subgenus is considered to be permanently taxonomically associated, i.e., the species that contains the biological type specimen ...
Cope
The cope (known in Latin as ''pluviale'' 'rain coat' or ''cappa'' 'cape') is a liturgical vestment, more precisely a long mantle or cloak, open in front and fastened at the breast with a band or clasp. It may be of any liturgical colour.
A c ...
Cope
The cope (known in Latin as ''pluviale'' 'rain coat' or ''cappa'' 'cape') is a liturgical vestment, more precisely a long mantle or cloak, open in front and fastened at the breast with a band or clasp. It may be of any liturgical colour.
A c ...
, 1875
*'' Edaphodon ubaghsi'' - Storms in Leriche, 1927
Species of questionable validity include:
*''Edaphodon leptognathus'' - Agassiz, 1843
*''Edaphodon sedgwickii'' - Agassiz, 1843 (possibly synonymous with ''E. agassizi'')