{[ promptMessage ]}

Bookmark it

{[ promptMessage ]}

Lab 7paleo fossils - Find this in your collection General...

Info iconThis preview shows page 1. Sign up to view the full content.

View Full Document Right Arrow Icon
This is the end of the preview. Sign up to access the rest of the document.

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 ...
View Full Document

{[ snackBarMessage ]}

Ask a homework question - tutors are online