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词汇 synapsid
释义

Definition of synapsid in English:

synapsid

noun sʌɪˈnapsɪdsɪˈnapsɪdsəˈnapsid
  • A fossil reptile of a Permian and Triassic group, the members of which show increasingly mammalian characteristics and include the ancestors of mammals.

    下孔亚纲的爬行动物。亦称MAMMAL-LIKE REPTILE

    Subclass Synapsida; includes the pelycosaurs and the therapsids

    Also called mammal-like reptile
    Example sentencesExamples
    • It has therefore been suggested that the mammalian class II gene clusters arose after the separation of the synapsids and the therapsids.
    • In reptiles and primitive synapsids, the right and left lower jaws are each made up of a number of bones, one of which is the dentary, or tooth-bearing, bone.
    • The early tetrapods of this time were amphibian-like animals that eventually gave rise to the reptiles and synapsids by the end of the Paleozoic.
    • Dimetrodon is neither a reptile nor a mammal, but a basal synapsid - that is, an early relative of the ancestors of mammals.
    • In the dry late Permian environment many types of synapsids and reptiles flourished.
    • Tall neural spines are also a characteristic of early synapsids.
    • These creatures succeeded the pelycosaurian synapsids as the rulers of the land, until they in turn were supplanted by the archosaurs during the early Triassic.
    • The temporal openings at the back of the skull that are shared by all synapsids were greatly enlarged, so that the remaining bone formed long arches.
    • The earliest occurring and phylogenetically most primitive synapsids are the ‘pelycosaurs’ of traditional terminology.
    • As Rowe points out, the early cynodonts were the first synapsids in which the brain filled the endocranial cavity.
    • Paleozoic synapsids have been the focus of many large-scale treatments over the past century and their anatomy and interrelationships are well known.
    • Conversely, if the fossil record does not accurately portray the first appearances of synapsids because preservation rates vary widely, then phylogenetic measures might yield a more reliable sequence of branching events.
    • The hypothesis that disparate groups of synapsids independently acquired mammallike characteristics has a long pedigree.
    • Land amniotes continued to diversify, and by the middle Pennsylvanian had split into several taxa, two of which would go on to dominate the Mesozoic and Cenozoic: the diapsids and the synapsids.
    • The second major group of reptiles, the synapsids, have only a single temporal opening.
    • This is an example of convergent evolution; synapsids and archosaurs evolved these features independently.
    • The possible parallel evolution of a jaw joint that allows extensive sliding in anomodonts is not unprecedented, because other synapsids independently evolved similar features.
    • Indeed, most workers recognized a geographical and temporal gap between Permo-Carboniferous ‘pelycosaurs’ and therapsid synapsids.
    • The amniotes in turn have two main groups: the synapsids (including mammals) and the sauropsids (including reptiles and their fossil relatives).
    • Assuming (likely, but not certain) that turtles diverged from Eureptilia after synapsids, there remains the problem of whether turtles have turbinals.

Origin

Early 20th century: from modern Latin Synapsida, from Greek sun- 'together' + apsis, apsid- 'arch'.

Definition of synapsid in US English:

synapsid

nounsəˈnapsid
  • A fossil reptile of a Permian and Triassic group, the members of which show increasingly mammalian characteristics and include the ancestors of mammals.

    下孔亚纲的爬行动物。亦称MAMMAL-LIKE REPTILE

    Subclass Synapsida; includes the pelycosaurs and the therapsids

    Also called mammal-like reptile
    Example sentencesExamples
    • These creatures succeeded the pelycosaurian synapsids as the rulers of the land, until they in turn were supplanted by the archosaurs during the early Triassic.
    • It has therefore been suggested that the mammalian class II gene clusters arose after the separation of the synapsids and the therapsids.
    • Conversely, if the fossil record does not accurately portray the first appearances of synapsids because preservation rates vary widely, then phylogenetic measures might yield a more reliable sequence of branching events.
    • The hypothesis that disparate groups of synapsids independently acquired mammallike characteristics has a long pedigree.
    • The possible parallel evolution of a jaw joint that allows extensive sliding in anomodonts is not unprecedented, because other synapsids independently evolved similar features.
    • In the dry late Permian environment many types of synapsids and reptiles flourished.
    • The early tetrapods of this time were amphibian-like animals that eventually gave rise to the reptiles and synapsids by the end of the Paleozoic.
    • Land amniotes continued to diversify, and by the middle Pennsylvanian had split into several taxa, two of which would go on to dominate the Mesozoic and Cenozoic: the diapsids and the synapsids.
    • As Rowe points out, the early cynodonts were the first synapsids in which the brain filled the endocranial cavity.
    • The temporal openings at the back of the skull that are shared by all synapsids were greatly enlarged, so that the remaining bone formed long arches.
    • The amniotes in turn have two main groups: the synapsids (including mammals) and the sauropsids (including reptiles and their fossil relatives).
    • Indeed, most workers recognized a geographical and temporal gap between Permo-Carboniferous ‘pelycosaurs’ and therapsid synapsids.
    • In reptiles and primitive synapsids, the right and left lower jaws are each made up of a number of bones, one of which is the dentary, or tooth-bearing, bone.
    • This is an example of convergent evolution; synapsids and archosaurs evolved these features independently.
    • The earliest occurring and phylogenetically most primitive synapsids are the ‘pelycosaurs’ of traditional terminology.
    • Tall neural spines are also a characteristic of early synapsids.
    • Assuming (likely, but not certain) that turtles diverged from Eureptilia after synapsids, there remains the problem of whether turtles have turbinals.
    • Dimetrodon is neither a reptile nor a mammal, but a basal synapsid - that is, an early relative of the ancestors of mammals.
    • The second major group of reptiles, the synapsids, have only a single temporal opening.
    • Paleozoic synapsids have been the focus of many large-scale treatments over the past century and their anatomy and interrelationships are well known.

Origin

Early 20th century: from modern Latin Synapsida, from Greek sun- ‘together’ + apsis, apsid- ‘arch’.

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