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Unformatted text preview: Find this in your collection. General Parts- Trilobite Trilobites Phylum Arthopoda - Subphylum Trilobitomorpha Trilobite means "3-lobed" Two pleural lobes Axial lobe Identification - Cephalon - Thorax - Pygidium Benthic, detritus feeders Detailed fossil record Among first shelly fossils in Cambrian Series of extinctions late Cambrian - Predation Permian: final extinction of the trilobites Question: How did the trilobites evolve through time? Wide range of body forms Typical primitive morphotype small pygidium, well developed eye ridges, simple lobed glabella, several thoracic segments, & flattened body Extremely spiney species and some that are entirely smooth Some have huge eyes w/ narrow bodies adapted to swimming (pelagic) Some have no eyes w/ wide bodies & long spines adapted for benthic env. Over time, thoracic segments were reduced to as few as 2 or increased to over 60 Overall body was elongated or widened Shapes & furrow patterns of glabella & shape of eye & eye ridges varied widely Development of simple eyes or compound eyes although many were blind Trilobites Through Time Find this in your collection. General Parts - Brachiopoda Phylum Brachiopoda "arm-foot" Solitary animal Bilateral symmetry Lophophore- fan-like, filter feeding part Marine, benthic -mostly sessile & epifaunal Suspension feeders Class Inarticulata Geologic Range Nearly all of Phanerozoic Greatest diversity Ordovician Most families extinct by end of Devonian Inarticulate Lingula Cambrian- Present Inarticulate characteristics Valves not usually hinged by teeth & sockets Complex system of muscles Chitinophosphatic shell Ornamentation: weak concentric growth lines Lack internal supports for lophophore & other skeletal features Class Articulata Definite hingement Teeth & sockets Shell composed of calcite Soft anatomy differs from that of an inarticulate Shape of shell can vary greatly -paleoecology Subdivisions of the Articulates - Shell structure - Nature of pedicle opening - Characteristics of brachidia (calcareous support of lophophore) Geologic History- Brachiopods
Earliest Brachiopods: Inarticulates, phosphatic shells Mid- Cambrian: Carbonate shells Articulate brachiopods diversify Silurian & Devonian Several extinction events that affected the diversity & abundance of brachiopods Several extinction events of late Paleozoic -affected diversity & abundance of brachiopods Only three groups in existence today Find this in your collection. General Parts - Class Crinoidea Class Crinoidea Phylum Echinodermata "Sea-lilies" Three main parts: Calyx, arms, and stem Vital organs encased in calyx Complete calyx rarely found Geologic History - Crinoids Ordovician Recent First appeared in Ordovician Golden age was Mississippian General Parts Class Blastoidea Class Blastoidea Phylum Echinodermata Armless bud-like calyx on a stem Readily apparent pentaradiate symmetry Budlike calyx 5 ambulacra radiating symmetrically from mouth 13 plates (3 basals, 5 radials, 5 interradials) enclose space not occupied by ambulacral areas Geologic History - Blastoids Ordovician Permian All are extinct!! Most numerous during Mississippian Lived in clear, shallow marine areas ...
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This note was uploaded on 03/27/2012 for the course GEOL 2413 taught by Professor Moody during the Spring '10 term at Texas A&M University, Corpus Christi.
- Spring '10