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Acanthodii

Class of primitive, fossil fish that had a true bony skeleton, a heterocercal tail fin, a persistent notochord, ganoid scales, and stout spines in front of the fins. The acanthodians lived ...

Acanthodii

Acanthodii   Quick reference

A Dictionary of Geology and Earth Sciences (5 ed.)

Reference type:
Subject Reference
Current Version:
2020

... ( acanthodians , spiny sharks ) Class of primitive, fossil fish, characterized by the presence of a true bony skeleton ( see bone ), a heterocercal tail fin , a persistent notochord , ganoid scales , and stout spines in front of the fins. The acanthodians lived from the Silurian to the Permian period and may be related to ancestors of the more modern bony...

Acanthodii

Acanthodii   Quick reference

A Dictionary of Zoology (5 ed.)

Reference type:
Subject Reference
Current Version:
2020
Subject:
Science and technology, Life Sciences
Length:
57 words

... Class of primitive, fossil fish that had a true bony skeleton, a heterocercal tail fin, a persistent notochord , ganoid scales , and stout spines in front of the fins. The acanthodians lived from the Silurian period to the Permian period and may be related to ancestors of the more modern bony fish....

Acanthodii

Acanthodii   Reference library

The New Oxford Dictionary for Scientific Writers and Editors (2 ed.)

Reference type:
Subject Reference
Current Version:
2009

... (cap. A; not Acanthodi) A class of extinct jawed fishes, sometimes regarded as a subclass of the Osteichthyes (bony fishes). Individual name and adjectival form: acanthodian (no...

Acanthodii

Acanthodii  

Class of primitive, fossil fish that had a true bony skeleton, a heterocercal tail fin, a persistent notochord, ganoid scales, and stout spines in front of the fins. The acanthodians lived from the ...
Teleostomi

Teleostomi  

A subgrade that comprises the ‘true’ fish (Osteichthyes), i.e. those with a terminal mouth, in contrast to the shark-like fish (Chondrichthyes) which have the mouth positioned beneath a substantial ...
Climatiiformes

Climatiiformes  

; class Acanthodii)One of the larger orders of fossil fish that had bony jaws and body skeleton, ganoid scales, a heterocercal tail, and stout spines located before the dorsal, anal, pectoral, and ...
Teleostomi

Teleostomi   Quick reference

A Dictionary of Zoology (5 ed.)

Reference type:
Subject Reference
Current Version:
2020
Subject:
Science and technology, Life Sciences
Length:
59 words

...comprises the ‘true’ fish ( Osteichthyes ), i.e. those with a terminal mouth, in contrast to the shark-like fish ( Chondrichthyes ) which have the mouth positioned beneath a substantial rostrum. In addition to the Osteichthyes, some authors also include the class of fossil Acanthodii in the Teleostomi. See also bony fish...

Climatiiformes

Climatiiformes   Quick reference

A Dictionary of Geology and Earth Sciences (5 ed.)

Reference type:
Subject Reference
Current Version:
2020

...One of the larger orders of fossil fish belonging to the class Acanthodii . They possessed bony jaws and body skeleton, ganoid scales, a heterocercal tail, and stout spines located before the dorsal, anal, pectoral, and pelvic fins. One of the better-known forms, Climatius , carried five additional pairs of fins along the belly and reached a length of only 8 cm. These ‘spiny sharks’ may actually be half-way between the sharks and the bony fish ( Osteichthyes...

Climatiiformes

Climatiiformes   Quick reference

A Dictionary of Zoology (5 ed.)

Reference type:
Subject Reference
Current Version:
2020
Subject:
Science and technology, Life Sciences
Length:
84 words

... ( spiny sharks ) ( class Acanthodii ) One of the larger orders of fossil fish that had bony jaws and body skeleton, ganoid scales, a heterocercal tail , and stout spines located before the dorsal , anal , pectoral , and pelvic fins . One of the better-known forms, Climatius , carried five additional pairs of fins along the belly and reached a length of only 8 cm. These fish may actually be half-way between the sharks and the bony fish....

Fishes

Fishes   Reference library

Encyclopedia of Evolution

Reference type:
Subject Reference
Current Version:
2005
Subject:
Science and technology, Life Sciences, Social sciences, Anthropology
Length:
5,375 words
Illustration(s):
2

...The living 58 species are few in proportion to the far more diverse extinct forms. Appearing in the early Silurian and persisting to the early Permian (430–250 mya), and thus living with Placoderms and early Elasmobranchs, as well as many jawless fishes at first, were the Acanthodii, or spiny sharks. The resemblance of this diverse group to sharks is superficial, and the two groups are distantly related. Acanthodians were mostly midwater feeders, some planktivorous, in both marine and fresh waters. Many characters support the hypothesis that this is the...

acanthodian

acanthodian noun   Reference library

Australian Oxford Dictionary (2 ed.)

Reference type:
English Dictionary
Current Version:
2004
Subject:
English Dictionaries and Thesauri
Length:
32 words
acanthodian

acanthodian noun   Quick reference

New Oxford American Dictionary (3 ed.)

Reference type:
English Dictionary
Current Version:
2015
Subject:
English Dictionaries and Thesauri
Length:
55 words
acanthodian

acanthodian noun   Quick reference

Oxford Dictionary of English (3 ed.)

Reference type:
English Dictionary
Current Version:
2015
Subject:
English Dictionaries and Thesauri
Length:
53 words

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