Chapter 1-7: Geologic Time & Osteology

Flashcards covering key geological concepts like time scales, dating methods, plate tectonics, and fundamental osteological terms and anatomical directions from the lecture notes.

Relative time

Putting events in chronological order, such as A then B then C.

Numerical time (Absolute time)

Assigning specific dates or numbers to events.

Error and bias

A measure of uncertainty around a hypothesis, considered a regular part of scientific measurement.

Biostratigraphy

The method of using animals, fossils, or plants preserved in rocks to correlate similar orders of rock layers across different locations.

Composite stratigraphic column

A comprehensive time scale created by combining various biostratigraphic data.

Geologic time scale

An organizational system for Earth's history, structured into eras, periods, and epochs.

Mesozoic Era

A major division of geologic time, meaning 'middle life'.

Cretaceous

A geological period, whose name means 'chalk', implying the deposition of marine layers in a warm environment.

Radiometric dating (Numerical dating or Radioisotopic dating)

A method used to date the formation and crystallization time of igneous rocks by analyzing minerals within them.

Magma

Liquid rock found beneath the Earth's surface.

Lava

Magma that has erupted onto the Earth's surface.

Crystallization time

The point at which elements within molten rock cool and solidify to form a solid rock.

Zircon

A highly resistant mineral crystal often sought for numerical dating purposes.

Uranium

An element commonly used for dating very old rocks due to its process of radioactive decay.

Radioactive decay

The process by which an unstable atomic nucleus loses energy by radiation, transforming into a different element over time (e.g., uranium transforming to lead).

Half-life

The amount of time required for 50% of the original radioactive material to transform into its decay product.

Uranium-lead dating

A radiometric dating method that measures the ratio of uranium to lead to determine the age of ancient rocks.

Carbon-14 (C-14) dating

A radiometric dating method with a short half-life (approximately 5700 years), primarily used for dating younger archaeological and anthropological materials.

Potassium-argon (K-Ar) dating

A radiometric dating method with a much longer half-life, used for dating deeper time fossils and older geological samples.

Detrital zircon

Zircon crystals that have been transported from their original formation location, requiring specific calculations to determine accurate ages.

Plate tectonics

The theory that describes the Earth's outermost layer as being fragmented into several large and small plates that are in constant motion.

Lithosphere

The rigid outermost shell of the Earth, consisting of the crust and upper mantle, which is broken into tectonic plates.

Asthenosphere

A ductile, semi-fluid layer of the Earth's mantle located beneath the lithosphere, allowing plates to move.

Convection

The process within the Earth's mantle where hot magma/mantle rises, spreads, cools, and sinks, creating cells that drive the movement of tectonic plates.

Divergent boundaries

Plate boundaries where two plates move away from each other, forming rift zones, rift valleys, or mid-ocean ridges.

Convergent boundaries

Plate boundaries where two plates move towards each other, resulting in either subduction or collision.

Subduction zones

A type of convergent boundary where one plate slides beneath another (e.g., an oceanic plate under a continental plate).

Collision zones

A type of convergent boundary where two continental plates collide, leading to mountain building (e.g., the Himalayas).

Transform boundary

A plate boundary where two plates slide horizontally past each other, characterized by earthquakes (e.g., the San Andreas Fault).

Earthquakes

Sudden ground motions caused by the release of built-up pressure when plates at transform or other boundaries suddenly slip past each other.

Fossil record evidence for plate tectonics

The presence of similar fossils across continents now separated, indicating they were once connected.

Continental fit

The observation that the shapes of continents appear to fit together like puzzle pieces, supporting the theory of plate tectonics.

Osteology

The scientific study of bones, including their structure, function, and relationship to other organisms.

Axial skeleton

The central part of the skeleton, consisting of the skull, vertebral column, and rib cage, forming the main axis of the body.

Appendicular skeleton

The parts of the skeleton that include the limbs (arms and legs) and the girdles (pectoral and pelvic) that attach them to the axial skeleton.

Humerus

The single bone of the upper arm.

Pelvic girdle

The bony structure that connects the legs to the axial skeleton; commonly referred to as the hips.

Pectoral girdle

The bony structure that connects the arms to the axial skeleton; commonly referred to as the shoulder system.

Homologous structure

A structure that is similar in different species of common ancestry, indicating shared evolutionary origin, even if function differs (e.g., the one-bone, two-bone, many-bones pattern in vertebrate limbs).

Analogous structure

A structure that serves a similar function in different species but has different evolutionary origins, meaning it evolved independently (e.g., the wings of bats, birds, and pterosaurs).

George Cuvier and Richard Owen

Pioneers in comparative anatomy who studied similarities and differences across animal groups and identified homologous structures.

Skeleton functions

The roles of the skeleton, including supporting body mass, protecting internal organs, and providing mechanical structures for movement.

Joints

Movable connections between bones that allow for various types of motion.

Sutures

Immovable or slightly movable fibrous joints found primarily between the bones of the skull.

Cartilage

A flexible connective tissue found in many parts of the body, including at joints, providing cushioning and reducing friction.

Ligaments

Strong fibrous connective tissues that connect bones to other bones, stabilizing joints.

Tendons

Dense fibrous connective tissues that connect muscles to bones.

Muscles

Tissues that contract to produce movement, typically working in opposing pairs (pull, not push).

Anatomical directions

Specific terms used to describe the relative position of bones or features within an organism, regardless of its orientation.

Bilateral symmetry

A body plan where an organism can be divided into two roughly mirror-image halves (left and right).

Anterior

Toward the nose or front end of an animal.

Posterior

Towards the tail or rear end of an animal.

Cranial

Towards the head or cranium, equivalent to anterior.

Caudal

Towards the tail or caudal region of an animal.

Dorsal

Towards the back or top surface of an animal.

Ventral

Towards the belly or bottom surface of an animal.

Medial

Towards the midline of an animal's body.

Lateral

Away from the midline of an animal's body, towards the sides (e.g., right lateral, left lateral).

Proximal

Closer to the point of attachment or origin of a limb or structure to the main body trunk (e.g., the shoulder is proximal to the elbow).

Distal

Further from the point of attachment or origin of a limb or structure to the main body trunk (e.g., the fingers are distal to the elbow).

Teeth

The hardest part of the body, used for understanding an animal's diet, and prominent in the mammalian fossil record.