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Two recent hypotheses about the evolution of biomineralization in arthropods and other groups of animals propose that it provides tougher defensive armor, [56] and that it allows animals to grow larger and stronger by providing more rigid skeletons; [57] and in either case a mineral-organic composite exoskeleton is cheaper to build than an all ...
Among the oldest known land arthropods are Trigonotarbids, members of an extinct order of spider-like arachnids. [5]Trigonotarbids share many superficial characteristics with spiders, including a terrestrial lifestyle, respiration through book lungs, and walking on eight legs, [6] with a pair of leg-like pedipalps near the mouth and mouth parts.
The evolutionary ancestry of arthropods dates back to the Cambrian period. The group is generally regarded as monophyletic, and many analyses support the placement of arthropods with cycloneuralians (or their constituent clades) in a superphylum Ecdysozoa. Overall, however, the basal relationships of animals are not yet well resolved. Likewise ...
Scientists discovered a 520-million-year-old fossilized larva with brains and guts intact, offering unprecedented insights into early arthropod evolution.
An intriguing arthropod ancestor. The 3D scans revealed two nearly complete specimens of Arthropleura that lived 300 million years ago. Both fossilized animals still had most of their legs, and ...
Trilobites belong to the Artiopoda, a group of extinct arthropods morphologically similar to trilobites, though only the trilobites had mineralised exoskeletons. Thus, other artiopodans are typically only found in exceptionally preserved deposits, mostly during the Cambrian period. The exact relationships of artiopods to other arthropods is ...
Some key events in the evolution of the arthropod body resulted from changes in certain Hox genes' DNA sequences. The trunks of arthropods comprise repeated segments, which are typically associated with various structures such as a pair of appendages, apodemes for muscle attachment, ganglia and (at least embryologically) coelomic cavities.
The subphylum Hexapoda (from Greek for 'six legs') or hexapods comprises the largest clade of arthropods and includes most of the extant arthropod species. It includes the crown group class Insecta (true insects), as well as the much smaller clade Entognatha, which includes three classes of wingless arthropods that were once considered insects: Collembola (springtails), Protura (coneheads) and ...