Paleontology and Marine Invertebrates Lecture Review

Comprehensive flashcards covering marine invertebrate paleontology, including Porifera, Cnidaria, Protista, Arthropoda, Bryozoa, Brachiopoda, Echinodermata, and Mollusca.

Archaeocyathids

Conical or vase-shaped Porifera with perforated inner and outer walls that lived from the beginning to the end of the Cambrian; they are preserved as calcite.

Stromatoporoids

Layered or dome-shaped Porifera structures composed of calcium carbonate; their internal structures include laminae and galleries.

Hexactinellida

Also known as glass sponges, these organisms possess skeletons made of a series of 6-rayed biogenic silica spicules arrayed $90^\circ$ from their neighbors.

Tabulata

Extinct colonial cnidarians (corals) such as Favosites and Halysites, characterized by calcite skeletons with individual corallites, tabulae, and septa.

Rugosa

Known as horn corals, these cnidarians feature calcite skeletons with vertical plates called septa in a radial pattern and gaps known as fossulae.

Scleractinian

Cnidarians with aragonite skeletons that dominate modern reefs; they often have a symbiotic relationship with photosynthetic algae called zooxanthellae.

Foraminifera

Protists with tests made of $CaCO_3$ or aragonite, exhibiting shapes like uniserial, biserial, or planispiral, and known for an alternation of generations.

Radiolaria

Zooplankton protists with intricate internal skeletons of biogenic silica that sink to accumulate as radiolarite sediment.

Diatoms

Protists with a two-part biogenic silica skeleton called a frustule; grouped as pennates or centrales.

Coccolithophores

Planktonic protists that form spherical skeletons from 10–30 $CaCO_3$ platelets, contributing to thick chalk deposits.

Ostracods

Arthropods with two hinged valves (carapaces) made of $CaCO_3$ that are often calcified and ornamented with ribs or ridges.

Conodonts

Nektonic gnathostomulida with phosphatic elements (coniform, ramiform, or pectiniform) that lived from the Cambrian to the Triassic.

Tagmatized

An anatomical state where different body regions, or tagmata, are specialized, as seen in the segmented bodies of arthropods.

Ecdysis

The process of molting where an arthropod's skeleton is shed and replaced as it grows.

Trilobites

Bottom-dwelling arthropods from the Cambrian to the Permian with an exoskeleton divided into cephalon, thorax, and pygidium.

Graptolites

Hemichordates preserved as delicate, lacy carbonaceous films on bedding planes, existing from the Early Ordovician through the Permian.

Zooecium

The individual hard part of a bryozoan zooid, which collectively forms the skeletal colony known as a zoarium.

Lophophore

A food-gathering and respiratory organ consisting of a ring of tentacles, found in both bryozoans and brachiopods.

Cheilostomes

The most highly evolved order of bryozoans, appearing in the Jurassic, characterized by box-like zooecia and an operculum (lid).

Pedicle

A fleshy stalk used by brachiopods to attach themselves to the seafloor substrate.

Linguliformea

A subphylum of inarticulate brachiopods with organophosphate shells, lacking teeth and sockets.

Rhynconellid

A subphylum of articulate brachiopods with calcareous shells, possessing teeth and sockets but lacking an anus.

Water Vascular System

A unique internal hydraulic mechanism in echinoderms used for locomotion, respiration, and food collection via tube feet (podia).

Madreporite

The perforated plate in echinoderms through which seawater enters the water vascular system.

Pelmatozoans

A group of fixed, usually stalked echinoderms that include crinoids and blastoids.

Aristotle’s Lantern

A complex jaw mechanism used by regular echinoids (sea urchins) to scrape seaweed from substrates.

Torsion

An anatomical process in gastropods where the visceral mass rotates $90^\circ$ to $180^\circ$ relative to the foot.

Nautiloidea

Cephalopods with external chambered shells and gently curved partitions called septa, linked by a siphuncle.

Ammonoidea

Extinct cephalopods from the Devonian to the Cretaceous with external coiled shells and complexly folded partition walls.

Coleoidea

Cephalopods with internal, reduced, or absent shells, including belemnites, cuttlefish, squid, and octopoda.