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Critters 3 is a 1991 American science fiction comedy horror Direct-to-video film and the third installment of the Critters series, directed by Kristine Peterson. The film stars Aimee Brooks , John Calvin , Katherine Cortez, Leonardo DiCaprio , in his film debut, and Don Keith Opper reprising his role as Charlie McFadden.
The trilobite body is divided into three major sections : 1 – cephalon; 2 – thorax; 3 – pygidium. Trilobites are so named for the three longitudinal lobes: 4 – right pleural lobe; 5 – axial lobe; 6 – left pleural lobe; the antennae and legs are not shown in these diagrams.
Chelicerata split from Mandibulata by the mid-Cambrian, as evidenced by stem-group chelicerates like Habeliida and Mollisonia present by this time. [2] The surviving marine species include the four species of xiphosurans (horseshoe crabs), and possibly the 1,300 species of pycnogonids (sea spiders), if the latter are indeed chelicerates. On the ...
Arachnomorpha is a proposed subdivision or clade of Arthropoda, comprising the group formed by the trilobites and their close relatives , Megacheira (which may be paraphyletic) and chelicerates. Under this proposed classification scheme, Arachnomorpha is considered the sister group to Mandibulata (including insects , crustaceans and myriapods ).
The Artiopoda is a grouping of extinct arthropods that includes trilobites and their close relatives. It was erected by Hou and Bergström in 1997 [5] to encompass a wide diversity of arthropods that would traditionally have been assigned to the Trilobitomorpha.
Chelicerates are in part defined by possessing chelicerate appendages, although crustaceans also possess chelate appendages. Chelicerates are more easily distinguished from other arthropods in lacking antennae and mandibles. Figure 4: Types of chelicerae: (A) jackknife, (B) scissor, and (C) 3-segmented chelate
Some studies recover Megacheira as closely related to chelicerates, while others recover them as outside the group containing Chelicerate and Mandibulata as stem-group euarthropods. [127] The placement of the Artiopoda (which contains the extinct trilobites and similar forms) is also a frequent subject of dispute. [128]
Aglaspidida is an extinct order of aquatic arthropods that were once regarded as primitive chelicerates.However, anatomical comparisons demonstrate that the aglaspidids cannot be accommodated within the chelicerates, [2] and that they lie instead within the Artiopoda, thus placing them closer to the trilobites. [3]