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The arthropod head problem has been tackled in three main ways in this regard, first by using genetic segmental markers to probe the obscure region in front of the mouth, especially in insects; second by looking at Hox gene expression patterns to detect patterns of homology among different arthropods; and third, by studying gene expression in ...
Nevertheless, despite being known from many specimens, disputes about its morphology, in particular its head appendages, have made it one of the most controversial of the Chengjiang taxa, and it has been discussed extensively in the context of the arthropod head problem. The genus is named after Fuxian Lake (Fuxian Hu), where it was unearthed.
In chelicerates and crustaceans, the cephalothorax is derived from the fusion of the cephalon and the thorax, and is usually covered by a single unsegmented carapace.In relation with the arthropod head problem, phylogeny studies show that members of the Malacostraca class of crustaceans have five segments in the cephalon, when not fused with the thorax to form a cephalothorax.
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 ...
Arthropod head problem – Dispute concerning the evolution of arthropods; Deep homology – Control of growth and differentiation by deeply conserved genetic mechanisms; Evolutionary developmental biology – Comparison of organism developmental processes
Cephalization is a characteristic feature of the bilaterians, a large group containing the majority of animal phyla. [3] These have the ability to move, using muscles, and a body plan with a front end that encounters stimuli first as the animal moves forwards, and accordingly has evolved to contain many of the body's sense organs, able to detect light, chemicals, and gravity.
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A study in 1992 estimated that there were 500,000 species of animals and plants in Costa Rica alone, of which 365,000 were arthropods. [ 38 ] They are important members of marine, freshwater, land and air ecosystems and one of only two major animal groups that have adapted to life in dry environments; the other is amniotes , whose living ...