Lecture 18 - Reptiles and dinosaurs Flashcards
Reptiles: when did they appear, what new characteristics did they bring, where do they mainly reside in, and what are the other interesting features?
320 mYa
Scales, hard-shelled eggs that could contain water (offspring not needed to stay near water) and ignore the tadpole stage which is where offspring are most vulnerable
Mainly tropical areas (they are cold-blooded)
- None are solely herbivorous
- They make up 30% of terrestrial vertebrate
- Reptiles are not monophyletic
- Vertebrate group most under threat
- Almost always ectotherms
Dinosaur clade groups after Archosauria and what they evolved into
Archosauria as the common ancestor:
- Crocodilia (crocodiles)
Evolved into the bird total group
Dinosaur clade groups in the bird total group and what they evolved into
Bird total-group:
- Aphanosauria
- Pterosauria (dimorphodon, pteranodon etc)
- Lagerpetidae
- Silesauridae
Evolved into dinosauria
Dinosaur clade groups in the dinosaur group and what they evolved into
Dinosauria:
Ornithischia (triceratops, ankylo, iguanodon etc)
Sauropodomorpha (Apatsaur, isisaur, amargasaur)
Evolved into theropoda
Dinosaur clade groups in the Theropoda group and what they evolved into
Theropoda:
Ceratorsauria, coelurosaruia, dilophosauridae, megalosauroidea, allosauroidea, etc
Evolved into Maniraptora
Dinosaur clade groups in the Maniraptora group and what they evolved into
Maniraptora:
Alverazsauria, Therizinosauria, Oviraptorosauria
Evolved into Paraves
Dinosaur clade groups in the Maniraptora group and what they evolved into
Paraves:
Eosinopteryx, Eumaniraptora (Troodontidae and Jinfengopteryx),
Evolved into Avealea
Dinosaurs in the Avialea group and what they evolved into
Avialea:
Anchiornis, Archeopterygidae, Jixianogornis, Jeholornis, etc
Evolved into Pygostalia
Organisms in the Pygostalia group
Pygostalia:
Current day birds
Alligators: head shape, habitat, size, lifespan, salt glands, and body colour
Short, wide snout in a U shape
Freshwater only (NA/China)
Can reach up to 14 feet
30-50 years
Not fully developed, can’t cope in a salty habitat
Dark colour: black, grey etc
Crocodile: head shape, habitat, size, lifespan, salt glands, and body colour
long, thin snout in a V shape
Can live in saltwater and freshwater and can be found everywhere
Can reach up to 19 feet
70-100 years
Fully developed, can expel salt if needed
Dark colour: black, grey etc
Turtle/tortoise shell
Part of its body – bone filling in the gaps between ribs, growing out from the spine
The years of dinosaurs ruling the planet and mass-extinction events
251mYa: end-Permian mass extinction wiped out 95% of species
215mYa: dinosaurs rule the planet (Triassic era)
200mYa: end-Triassic extinction, many species of Archosaurs died out
145mYa: end-Jurassic, Cretaceous period begins
66mYa: End-Cretaceous, all species except birds, small mammals, crocodiles, and other small organisms extinct
Earliest dinosaurs
Archosaurs:
Reptiles with upright posture, pillar-like legs, and holes behind the eyes
Three groups of marine reptiles: what are they, what were they like, and how long did they live (in mYa)?
Ichthyosaurs: dolphin-like, sclerotic eye rings (250-90)
Plesiosaurs: long-necked, lived everywhere (215-66)
Mosasaurs: large lizards related to monitor lizards (86-66mYa)
These were reptiles that had returned to the seas, they were not dinosaurs (dinos were not aquatic)
Pterosaurs: what are they, where did they come from, how long did they live, and what are their significant features?
Flying dinosaurs
Phylogenetic origin uncertain (Lagerpetids??)
230mYa - 66mYa
- First vertebrate with powered flight
- Could not roost
- Includes quetzalcoatlus, the largest flying animals to ever exist
Pterosaurs: what are they, where did they come from, how long did they live, and what are their significant features?
Flying reptiles - NOT dinosaurs but closely related
Phylogenetic origin uncertain (Lagerpetids??), is a type of archosaur
230mYa - 66mYa
- First vertebrate with powered flight
- Could not roost
- Includes quetzalcoatlus, the largest flying animals to ever exist
- Pteroid bone only found in them
- Non-pterodactyloid - small, have tails, early forms
- Pterodactyloid - large, no ail, most diverse group
Stegosaurs: what are they, where did they live, how long did they live, and what might the back plates have been used for?
Quadrupedal dinosaurs with plates on their back
Every continent excluding Antartica (so far)
200mYa - 145mYa
- Initially thought to have plates as a defence mechanism but, since plates had weak support and capillaries were suggested to be near plates, it is likely that they were used for thermoregulation
Saurischia: what does this mean and what species are part of this?
“Reptile-hipped” dinosaurs - Forward-oriented pubic bones
- Theropoda (Tyrannosaurs, etc)
- Sauropoda (Diplodocus etc)
Ornithischia: what does this mean and what species are part of this?
“Bird-hipped” dinosaurs - Backward-oriented pubic bones
- Ornithopoda (Hadrosaurs etc)
- Thyreophora (Stegosaurs etc)
- Marginocephalia (Triceratops etc)
Did dinosaurs have feathers?
Indentations in fossilised bones suggest dinosaurs may have had bones
Preserved feather in a 99 million-year-old amber suggests feathers existed back then
What colour were dinosaurs?
Melanosomes can be found present in some well-fossilised bones which suggest dinosaurs were a chestnut/reddish-brown colour
Oviraptor egg colours
A recent identification of bird egg pigments protoporphyrin and biliverdin in Oviraptor shells from China suggest eggs were blue-green,
like many modern birds
Synapsid: what is it and what animals are an example of it?
A vertebrate with one major hole (temporal fenestra) in their skull
Most mammals and mammal-like reptiles
Diapsid: what is it and what animals are an example of it?
A vertebrate with two major holes (temporal fenestrae) in their skull
Most reptiles and all birds
Ectotherm: what is it and what animals are ectotherms?
An organism that relies on the environment to regulate its temperature
Reptiles, fishes, amphibians, etc
Endotherm: what is it and what animals are endotherms?
Organisms that thermoregulate themselves
Mammals, birds, etc
Therapsids: what are they?
“Mammal-like” synapsid reptiles that flourished during the Permian-Triassic periods until the last forms were extinct during the Cretaceous period
These are considered ancestors of the mammals
