Archaeostraca
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The term "Archaeostraca" refers to an extinct order of crustaceans that existed during the Paleozoic Era. These early forms, appearing in the early Paleozoic, shared a body plan with aquatic arthropods from the Cambrian seas. However, they lacked key characteristics of true crustaceans, such as chewing head appendages. The fossil record indicates that many fundamental crustacean features had already evolved by the Cambrian Period. While the exact classification and interrelationships of crustacean groups are still debated, molecular data and further fossil discoveries are expected to clarify evolutionary pathways.123
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crustaceanAnnotated classification†Order ArchaeostracaDevonian to Triassic.†Order HoplostracaCarboniferous.Order LeptostracaPermian to present; bivalved carapace encloses 8 pairs of leaflike limbs; movable rostrum; telson with caudal rami; marine; about 10 species.
Read More†Order ArchaeostracaDevonian to Triassic.†Order HoplostracaCarboniferous.Order LeptostracaPermian to present; bivalved carapace encloses 8 pairs of leaflike limbs; movable rostrum; telson with caudal rami; marine; about 10 species.
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malacostracanAnnotated classification†Order Archaeostraca Early Ordovician to Permian; carapace bivalved and hinged; both antennae with two branches; 6 families. †Order Hoplostraca Late Carboniferous; carapace short; antennae 2 one-branched, raptorial in form; 1 family. Order Leptostraca (visored
Read More†Order Archaeostraca Early Ordovician to Permian; carapace bivalved and hinged; both antennae with two branches; 6 families. †Order Hoplostraca Late Carboniferous; carapace short; antennae 2 one-branched, raptorial in form; 1 family. Order Leptostraca (visored
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