Lesson 4 Vocab: Mosasauroids

Mosasauroids

A group of aquatic lepidosaurs from the Late Cretaceous. Best known for the most derived members, the mosasaurs.

Baron Georges Cuvier

Known as the father of comparative anatomy and palaeontology.

Squamata (informally, squamates)

The group of lepidosaurs that includes all modern lizards and snakes.

Anguimorpha (informally, anguimorphs)

The group of lepidosaurs that includes extant animals such as alligator lizards, glass lizards and legless lizards.

Intramandibular joint

A joint in the middle of each lower jaw of mosasauroids and snakes that helps expand the gape of the animal during feeding.

Intermandibular joint

The connection point between the two halves of the lower jaw, found at the front of the mouth.

Pterygoid teeth

Teeth found on the pterygoid bones in the throat. Adapted to stop slippery prey from slipping out of the mouth.

Pythonomorpha (informally, pythonomorphs)

The clade containing mosasauroids and snakes. Still a contentious grouping.

Quadrate

The large, mobile bone that functions as the hinge for the jaw in pythonomorphs. It also serves to support the middle ear structures.

Eon

A subdivision of geologic time that divides Earth's history into four units. Eons are divided into eras. Typically span half a billion years or more. Example: Phanerozoic Eon.

Era

A subdivision of geologic time that divides eons into smaller units. Eras are subdivided into periods. Typically span hundreds of millions of years. Example: Mesozoic Era.

Period

A subdivision of geologic time that divides eras into smaller units. Periods are further subdivided into epochs and ages. Typically span tens of millions of years. Example: Cretaceous Period.

Age

A subdivision of geologic time that divides periods and epochs into smaller units. Typically span millions of years. Example: Maastrichtian Age.

Cenomanian

The first of six ages within the Late Cretaceous. Began over 100 million years ago.

Turonian

The second of six ages within the Late Cretaceous.

Coniacian

The third of six ages within the Late Cretaceous.

Santonian

The fourth of six ages within the Late Cretaceous.

Campanain

The fifth of six ages within the Late Cretaceous.

Maastrichtian

The last of six ages within the Late Cretaceous.

Mosasauridae

The clade containing all mosasauroids more derived than the Aigialosauridae.

Dolichosauridae (informally, dolichosaurs)

A family of semi-aquatic mosasauroids that may be the sister group to mosasauroids. Includes genera such as Adriosaurus and Pontosaurus.

Aigialosauridae (informally, aigialosaurs)

The earliest and most basal mosasauroids. They were long slender lizards that lived in coastal environments. Includes genera such as Aigialosaurus.

Carsosaurus

Basal mosasauroid in the lineage leading to tylosaurs and tethysaurs. They lived during the Cenomanian and were viviparous.

Komensaurus

Basal mosasauroid in the lineage leading to tylosaurs and tethysaurs. They lived during the Cenomanian.

Tethysaurinae (informally, tethysaurines)

A mosasaur sub-family that still had primitive, terrestrial characteristics in their limbs and girdles. Includes genera such as Tethysaurus and Pannoniasaurus.

Yaguarasaurinae (informally, yaguarasaurs)

A mosasaur sub-family that likely represents the transition from semi-aquatic to fully-aquatic morphologies.

Halisaurinae (informally, halisaurs)

A mosasaur sub-family of uncertain relationships. They had a large stratigraphic and geographic range and were generally four to six metres long. Inclues genera such as Halisaurus and Pluridens.

Plioplatecarpinae (informally, plioplatecarpines)

The longest-lived mosasaur sub-family. Fast and flexible animals with a relitively unspecialized mosasaur body plan. Includes genera such as Platecarpus and Plioplatecarpus.

Ratchet feeding

A way to consume large prey, where the top jaw and the bottom jaw alternately "walk" down a prey item one jaw at a time, slowly inching the prey down the throat.

Tylosaurinae (informally, tylosaurines)

A mosasaur sub-family characterized by an overhanging upper jaw. Includes genera such as Tylosaurus, Hainosaurus and Taniwhasaurus.

Dallasaurus

A Turonin mosasauroid from Texas. A mosasauroid basal to the mosasaurine lineage.

Clidastes

The most basal mosasaurine, with aquatic adaptations including flippers. Long slender body and a shorter tail than other mosasaurs.

Mosasaurinae (informally, mosasaurines)

A mosasaur sub-family characterized by complex limb bones and ossified, blocky ankle and wrist elements. Includes genera such as Mosasaurus, Plotosaurus and Moanasaurus.

Prognathodontinae (informally, prognathodontines)

A mosasaur sub-family characterized by blunt snouts and projecting teeth on the premaxilla. Includes genera such as Prognathodon and Plesiotylosaurus.

Premaxilla

A pair of small bones at the very tip of the top jaw. Often, these bones bear teeth.

Globidensinae (informally, globidensines)

A mosasaur sub-family characterized by rounded, bulbous teeth. These mosasaurs were durophagous, with robust skulls. Includes genera such as Globidens and Carinodens.

Mosasaurus

The first discovered and described genus of mosasaur. Named the Grande Animale de Maastrict upon its discovery. Their large size and cutting teeth made them apex predators.

Mosasaur

A general term referring to a large, predatory marine squamate with four flippers and a flattened tail that lived during the Late Cretaceous

Serpentes

The suborder that contains all living and extinct snakes. These animals are all elongate, carnivorous and have reduced or absent legs.

Kinetic

Joints and sutures in the skeleton with the ability to move.

Paleopathology

The study of injury and disease as preserved in fossils.

Callus

An extra growth of ossified tissue which grows around the site of an injury.

Intraspecific interaction

Occasions where individuals of the same species come into contact.

Interspecific interaction

Occasions where individuals of different species come into contact.

Goronyosaurus

A crocodile-like freshwater mosasaur of uncertain relationships. Found in the Maastrichtian of Niger and Nigeria.

Hypocercal

A type of heterocercal tail fin, where the bottom lobe is longer than the top one.