Callorhinchidae
''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'' ...
(sometimes assigned to Edaphodontidae). As a member of the Chimaeriformes, ''Edaphodon'' was a type of rabbitfish, a
cartilaginous fish
Chondrichthyes (; ) is a class of jawed fish that contains the cartilaginous fish or chondrichthyans, which all have skeletons primarily composed of cartilage. They can be contrasted with the Osteichthyes or ''bony fish'', which have skeleto ...
related to
shark
Sharks are a group of elasmobranch cartilaginous fish characterized by a ribless endoskeleton, dermal denticles, five to seven gill slits on each side, and pectoral fins that are not fused to the head. Modern sharks are classified within the ...
Aptian
The Aptian is an age (geology), age in the geologic timescale or a stage (stratigraphy), stage in the stratigraphic column. It is a subdivision of the Early Cretaceous, Early or Lower Cretaceous epoch (geology), Epoch or series (stratigraphy), S ...
age of the
Lower Cretaceous
Lower may refer to:
* ''Lower'' (album), 2025 album by Benjamin Booker
* Lower (surname)
* Lower Township, New Jersey
*Lower Receiver (firearms)
* Lower Wick Gloucestershire, England
See also
* Nizhny
{{Disambiguation ...
and vanished in the
Pliocene
The Pliocene ( ; also Pleiocene) is the epoch (geology), epoch in the geologic time scale that extends from 5.33 to 2.58 It was most prominent during the Late
Cretaceous
The Cretaceous ( ) is a geological period that lasted from about 143.1 to 66 mya (unit), million years ago (Mya). It is the third and final period of the Mesozoic Era (geology), Era, as well as the longest. At around 77.1 million years, it is the ...
. 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 () is an island country in the southwestern Pacific Ocean. It consists of two main landmasses—the North Island () and the South Island ()—and List of islands of New Zealand, over 600 smaller islands. It is the List of isla ...
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 (also known as the Antarctic Ocean), it contains the geographic South Pole. ...
).
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. Semi-transparent and non-porous, it is usually covered by a tough and fibrous membrane called perichondrium. In tetrapods, it covers and protects the ends of long bones at the joints ...
. 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 more recent 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 ''cret ...
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'' ...
'' measure in length; the largest ''E. sedgwickii'' mandibular tooth plates reach , and ''E. snowhillensis'' mandibular tooth plates also reached . According to living callorhynchid and rhinochimaerid specimens, palatine plate represents 4 percent of the length between gill opening and body tip excluding elongated tail. Based on this calculation, the species ''E. barberi'', ''E. mirificus'', and ''E. snowhillensis'' have been estimated at over in length, with one individual of ''E. mirificus'' reaching .
Agassiz
Jean Louis Rodolphe Agassiz ( ; ) FRS (For) FRSE (May 28, 1807 – December 14, 1873) was a Swiss-born American biologist and geologist who is recognized as a scholar of Earth's natural history.
Spending his early life in Switzerland, he recei ...
, 1843 (
type species
In International_Code_of_Zoological_Nomenclature, 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 spe ...
Cope
A cope ( ("rain coat") or ("cape")) is a liturgical long mantle or cloak, open at the front and fastened at the breast with a band or clasp. It may be of any liturgical colour.
A cope may be worn by any rank of the Catholic or Anglican clerg ...
Cope
A cope ( ("rain coat") or ("cape")) is a liturgical long mantle or cloak, open at the front and fastened at the breast with a band or clasp. It may be of any liturgical colour.
A cope may be worn by any rank of the Catholic or Anglican clerg ...
, 1875
*'' Edaphodon ubaghsi'' - Storms in Leriche, 1927
Species of questionable validity include:
*''Edaphodon leptognathus'' -
Agassiz
Jean Louis Rodolphe Agassiz ( ; ) FRS (For) FRSE (May 28, 1807 – December 14, 1873) was a Swiss-born American biologist and geologist who is recognized as a scholar of Earth's natural history.
Spending his early life in Switzerland, he recei ...
, 1843
*''Edaphodon sedgwickii'' -
Agassiz
Jean Louis Rodolphe Agassiz ( ; ) FRS (For) FRSE (May 28, 1807 – December 14, 1873) was a Swiss-born American biologist and geologist who is recognized as a scholar of Earth's natural history.
Spending his early life in Switzerland, he recei ...