Lecture 13A: Paleozoic Life

Agnathans

Jawless fish; oldest know discovery was in the Lower Cambrian, but diversification in Ordovician.

Anomalocaris

Top predator of the Cambrian.

Anoxic

An environment that lacks oxygen (ex: Burgess Preservation).

Apex predator

An animal at the top of the food chain that has no natural predators; not hunted by any other creature in its ecosystem.

Archaeocyathids

Marine sponges that lived during the Cambrian period; some of the earliest known reef-building organisms.

Burgess Shale

Discovered in 1909 on an expedition to collect Cambrian trilobites in the Canadian Rockies by Charles Walcott; one of the major lagerstatten.

Cambrian explosion

Refers to the seemingly instantaneous appearance of many varied animals in the early to middle Cambrian.

Cloudina

One of the earliest know animal fossil with a mineralized skeleton; "tube-dwelling worm" and first organism with a hard shell.

Conodonts

Index fossil for the Ordovician; class of agnathans that evolve in Cambrian but become abundant in the Ordovician.

Coral reef

Underwater structures formed by tiny animals called coral polyps; first appeared in the Ordovician period. Examples include Rugose and Tabulate corals.

Fossil

The remains or traces of ancient plants or animals that have been preserved in rocks over millions of years.

Gastropods

Evolved in the Cambrian period; includes snails. Predators and scavengers, played a role in the decline of stromatolites by grazing. Diversified significantly during the Ordovician.

Great Ordovician Biodiversification Event (GOBE)

This was characterized by an increase in species, genus, family, and order; tripled global diversity.

Global cooling

Caused the Ordovician mass extinction event.

Lagerstatten

An environment where fossils are exceptionally well-preserved, often including soft tissues.

Mass extinction event

A rapid and widespread decrease in the number of species on Earth; occurred at the end of the Ordovician, Devonian, Permian, Triassic, and Cretaceous periods.

Nautiloids

Top predator of the Ordovician; a group of marine mollusks with coiled or straight shells.

Non-vertebrate

Animals that do not have a backbone or spine. This group includes creatures like insects, worms, jellyfish, and snails.

Ordovician mass extinction event

The first great Mass Extinction; likely cause was a global glaciation event.

Radiation

The rapid increase and diversification of life forms or species over a relatively short period of geological time.

Rugose corals

Horn corals

Sea stars

Top predator of the Ordovician; a marine animal with a star-shaped body that lives on the ocean floor.

Sponge reef

Cambrian; underwater structures made by sponges, built from the skeletons of sponges and provide a habitat for various marine life.

Tabulates

Honeycomb corals

Treptichnus pedum

Trace fossil of the Cambrian; preserved worm burrow.

Trilobite

Index fossil of the Cambrian.

Vertebrate

An animal with a backbone or spinal column; Ordovician marks the biodiversification (or radiation) of our own subphylum.

Cambrian explosion, trilobites, treptichnus pedum, Burgess Shale Lagerstatten, and Anomalocaris.

What were the major biology events of the Cambrian?

Trilobites

What was the index fossil of the Cambrian?

Treptichnus pedum

What trace fossil defined the base of the Cambrian?

Ordovician

What period did Bryozoans show up?

Sponges

What were the reefs denominated by during the Cambrian period?

Rugose and Tabulates corals

Which types of corals dominated Ordovician reefs?

Graptolites

What is the index fossil of the Ordovician?

Jawless fish

What were the earliest vertebrates?

Cephalopod nautiloids and sea stars

What were the top predators of the Ordovician?