Week 5 Vocab: Birth, Growth and Reproduction

Amniotes

A group of tetropods that lay eggs equipped with a special water-tight membrane layer called an amnion.

Histology

The study of bone microstructure as it relates to bone growth

Line of Arrested Growth (LAG)

A dark band visible in a histological cross-section of a bone that formed during a time when the bone was not growing; LAGS are generally assumed to form annually in response to regular seasonal periods of food scarcity

External Fundamental System

A closely spaced series of LAGs, towards the outside of a bone section, formed as growth slows and, eventually, stops.

Ontogenetic Changes

Anatomical changes that occur during an individual's life (growth).

Non-isometric ontogenetic changes.

Changes in the relative proportions of an animal

as it grows, that are not simply changes

resulting from a general increase in size. (E.g. Fast growth of horns vs slow growth of body).

Isometric ontogenetic changes

Changes in absolute size but not

proportions of an animal.

Sexual Dimorphism

Differences between males and females of a given species, beyond genitalia.

Medullary Bone

Bone that stores calcium in preparation for laying eggs- useful in identification of female dinosaurs.

Osteocyte

Bone cell, formed by bone-creating cells (osteoblasts) becoming surrounded and trapped by the product they secreted.

Predator satiation

A reproductive strategy where herbivores produce lots of offspring and provide little to no parental care, as opposed to producing fewer offspring and protecting them. E.g. Sea Turtles or Sauropods

Lamellar bone

Striated, regularly structured bone tissue which is more visible in the bones of young dinosaurs.

Haversian bone

Also called 'secondary bone'; this is bone tissue that has been secondarily remodelled during the dinosaur's lifetime- more evident in older dinosaurs.

Vascularity

Lots of spaces in bone tissue, due to the presence of blood vessels required for bone formation when the animal was allowed. More evident in the bone tissue of young dinosaurs.