Geologic Time, Mass Extinctions, and Dinosaur Physiology

Flashcards covering key vocabulary and concepts from lecture notes on geologic time, mass extinctions, and dinosaur physiology.

Geologic Time

Marked by significant events like the oldest fossils, eukaryotes, and vertebrates.

Paleozoic Era

Era from 542-250 Million Years Ago including the Cambrian and Ordovician Radiation, several extinctions, and the advent of chordates, vertebrates, and life on land.

End Permian Mass Extinction

Significant loss of species with 90-96% marine and 70% terrestrial species lost, marking a transition to modern fauna.

Tetrapods

Includes amphibians, reptiles, birds, and mammals; known from the Late Devonian and are the first terrestrial vertebrates.

Amniotes

Two major branches: Sauropsida and Synapsids.

Synapsids

Ruled the Permian period; includes Therapsids that were carnivorous/herbivorous, possibly endothermic, and dominated the Late Permian.

Sauropsida

Ruled the Mesozoic Era; diverse group that includes Archosaurs, which gave rise to crocodiles, pterosaurs, and dinosaurs.

Ornithischia

One group of Dinosauria; defined as 'bird-hipped' Pubis Points Backward, very diverse group of Herbivores

Saurischia

The other group of Dinosauria; includes Sauropods and Theropods

Poriferans

Sponges with asymmetrical body plans and no true tissues.

Cnidarians

Corals and Jellies with radial symmetry and two tissue layers (diploblastic).

Bilaterians

Have bilateral symmetry and three tissue layers (triploblastic); divided into Protostomes and Deuterostomes.

Protostomes

"Mouth First" development; includes Arthropoda, Brachiopoda, Mollusca, and Annelida.

Deuterostomes

"Anus First" development; includes Echinodermata, Hemichordata, and Chordates.

Phylum Chordata

Defined by bilateral symmetry, a coelom, deuterostome development, metamerism, cephalization, notochord, dorsal tubular nerve cord, pharyngeal pouches, endostyle, and postanal tail.

Subphylum Vertebrata

Characterized by jaws, limbs (tetrapods), and amniotic egg.

Amniotic Egg

Allows vertebrates to become fully terrestrial; has a protective outer shell permeable to gases but impermeable to water.

Mass Extinctions

Affects many different, distantly related groups quickly, reducing diversity of life and niches.

Causal Agent

The initial phenomenon that starts an extinction event (e.g., asteroid impact, volcanic eruption).

Killing Agent

The particular aspect of the phenomenon that does the killing (e.g., atmospheric dust, carbon dioxide, thermal pulse).

Killing Mechanisms

The physiological change produced by the killing agent (e.g., starvation, asphyxiation, heat load).

Disaster Taxa

Long-ranging opportunist/generalists that proliferate when there is no competition.

Lilliput Effect

Small organisms persist after extinction.

Sepkoski’s Three Great Evolutionary Faunas

Cambrian, Paleozoic, and Modern Faunas characterized by specific dominant groups.

Endothermic

Internal heat source, fast metabolism, homeothermic.

Ectothermic

External heat source, slow metabolism, heterothermic.

Gigantothermy

Ectothermic but maintained a constant body temperature by growing large.

Mesozoic Marine Revolution

All different major modes of life we know today are occupied, infaunal modes of life are fully exploited.

Marine Sauropsids

First reptiles to return to an aquatic life were mesosaurs, with long needle-like teeth for catching small fish and webbed hands and feet for paddling.

Ichthyosaurs

Evolved from land-dwelling reptile, modified body for life in sea, fins on back and tail, modification of limbs to form flippers

Plesiosaurs

Evolved from a land-dwelling reptile, including long-necked forms such as Pliosaurs and Elasmosaurs, as well as large-headed, short-necked forms.

Mosasaurs

Late Cretaceous only; survived until the very end of Cretaceous, with forelimbs modified into powerful webbed flippers and a powerful, deep tail.

Theropods

Obligate Bipeds, Fast & Agile, Sharp Teeth, Big Claws (Either Fore or Hind Limbs), Large Eyes = Good Vision, carnivores, includes birds

Trace Fossils

Tell you where the animal was active (preferred environment), Social Behavior (solitary or herds), Interaction between species, How they walked (locomotion), Speed

Encephalization Quotient

Brain size vs. body size