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Some, if not all, lissamphibians share the following characteristics. Some of these apply to the soft body parts, hence do not appear in fossils. However, the skeletal characteristics also appear in several types of Palaeozoic amphibians: [6] Double or paired occipital condyles; Two types of skin glands (mucous and granular)
Most labyrinthodonts had special sense organs in the skin, forming a lateral line organ for perception of water flow and pressure, like those found in fish and a number of modern amphibians. [10] This would enable them to pick up the vibration of their prey and other waterborne sounds while hunting in murky, weed filled waters.
The largest living amphibian is the 1.8 m (5 ft 11 in) South China giant salamander (Andrias sligoi), but this is dwarfed by prehistoric temnospondyls such as Mastodonsaurus which could reach up to 6 m (20 ft) in length. [7] The study of amphibians is called batrachology, while the study of both reptiles and amphibians is called herpetology.
However, most tetrapod species today are amniotes, most of which are terrestrial tetrapods whose branch evolved from earlier tetrapods early in the Late Carboniferous. The key innovation in amniotes over amphibians is the amnion , which enables the eggs to retain their aqueous contents on land, rather than needing to stay in water.
A chordate (/ ˈ k ɔːr d eɪ t / KOR-dayt) is a deuterostomal bilaterian animal belonging to the phylum Chordata (/ k ɔːr ˈ d eɪ t ə / kor-DAY-tə).All chordates possess, at some point during their larval or adult stages, five distinctive physical characteristics (synapomorphies) that distinguish them from other taxa.
Zoologists characterize amniotes in part by embryonic development that includes the formation of several extensive membranes, the amnion, chorion, and allantois. Amniotes develop directly into a (typically) terrestrial form with limbs and a thick stratified epithelium (rather than first entering a feeding larval tadpole stage followed by ...
[17] [18] Unlike other modern amphibians (frogs and salamanders) the skull is compact and solid, with few large openings between plate-like cranial bones. The snout is pointed and bullet-shaped, used to force their way through soil or mud. In most species the mouth is recessed under the head, so that the snout overhangs the mouth. [10]
The origins and evolutionary relationships between the three main groups of amphibians (apodans, urodeles and anurans) is a matter of debate.A 2005 molecular phylogeny, based on rDNA analysis, suggested that the first divergence between these three groups took place soon after they had branched from the lobe-finned fish in the Devonian (around 360 million years ago), and before the breakup of ...