Graptolite
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Graptolites are a group of colonial animals, members of the subclass Graptolithina within the class Pterobranchia. These filter-feeding organisms are known chiefly from fossils found from the Middle C
Diversity of graptolite colony forms
A hypothetical graptolite zooid inside its theca, reconstructed based on living pterobranchs
Pendeograptus fruticosus from the Bendigonian Australian Stage (Lower Ordovician; 477–474 mya) near Bendigo, Victoria, Australia. There are two overlapping, three-stiped rhabdosomes.
Deuterostome
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Deuterostomes are bilaterian animals of the superphylum Deuterostomia, which are typically characterized by their blastopore becoming their anus during embryonic development. Deuterostomia comprises t
Early deuterostomes and their modern counterparts
