dino final

Clade

A grouping of organisms based on their hypothesized evolutionary history, consisting of a common ancestor and all of its descendants

Dinosaur/Dinosauria

Greek: "dino" = terrible, "saur" = lizard

Dinosaurs (clade Dinosauria) are a group of animals that share a unique common ancestor

Synapomorphy

A shared trait that helps define a group

Empirical

things that can be recognized by the senses (sight, touch, etc)

based on observation or experiment

Hypothesis

a proposed explanation for a set of observations about the natural world

Law

a generalization about some aspect of the natural world that appears to be true in all cases

Normative

the culture dictates how observations are interpreted and what questions are worth asking

Theory

an explanation about some aspect of the natural world that has been repeatedly tested and confirmed

Body fossil

physical remains of an organism

Bone beds

sites where hundreds or thousands of fossils are preserved (quantity > quality)

Fossil

the preserved remains of a prehistoric organism

Lagerstätte

(German: lager "storage, lair", stätte "place": a fossil deposit with exceptional preservation)

Often anoxic (oxygen limited) environments that preserve many individuals with evidence of soft tissue

Minerals

solids with a well-defined chemical composition and crystal structure

Molecular fossil

molecules preserved and extracted from fossils

ancient DNA, proteins, and lipids (fats)

Trace fossil

remains of the behavior of an organism but not the organism itself

trackways/footprints, coprolites, bite marks, scratch marks

Erosion

weathering of rock by wind and water

Igneous rocks

formed through the cooling and solidification of magma and lava

no good for dino fossils

Mesozoic

Age of dinosaurs

(Greek: "meso" = middle; "zoa" = life)

Metamorphic rocks

formed by the transformation of other rocks through extensive heat and pressure

no good for dino fossils

Paleontology

the branch science that deals with the discovery, collection, and study of fossils

Sedimentary rocks

formed by the accumulation and cementation of sediment at the Earth's surface

GREAT for finding dino fossils

Sedimentation

the laying down of dirt and mud, eventually turning into layers of rock

Biostratigraphy

Fossil succession

(greek: "bios" = life)

Dating rocks based on their fossils

Chronostratigraphy

study of ages of rock strata in relation to time, determines relative and absolute ages of rock strata

Index fossil

fossils from organisms that had a broad distribution but were short-lived

These fossils are particularly useful for correlating geologic columns between locations

Lithostratigraphy

(greek: "lithos" = rock)

Dating rocks based on their order and mineral composition

Acetabulum

Hole in the pelvis that allows the femur to lock in place

Gave dinos an upright stance like birds and mammals

Allows dinos to tuck their legs under their body

Anterior

Front/Closer to head

Distal

Further from the center of the body

Dorsal

Back

Fenestra

Holes in the skull

Mandibular fenestra (hole in jawbone)

Naris (nostril)

Antorbital fenestra (behind nostril, in front of eye)

Orbit (eye socket)

Postorbital fenestrae (behind eye)

Kinetic skull

significant movement of skull bones relative to each other

Many pieces, lots of flexibility

Law of natural selection

how populations become better adapted to their environment by the preservation of favorable traits

Posterior

Butt/tail

Proximal

Closer to the center of the body

Theory of common descent

all living things are connected through a series of common ancestors

Ventral

Belly

Cladistics

formalized process of determining evolutionary relationships (phylogenies)

Method for figuring out who is more closely related to who

Cladogram

an evolutionary tree (phylogeny) made from cladistic analyses

Comparative anatomy

the study of similarities and differences between species

Evolutionary tree/phylogeny

Diagram showing evolutionary relationships among species

Monophyletic clade

A group made up of a common ancestor and all of its descendants

Paraphyletic clade

A group made up of a common ancestor and some, but not all of its descendants

Useful for constraining the ancestral condition

Taxa

(singular - taxon) any unit used in the biological classification of life (taxonomy)

Can be populations, species, or larger clades

Evaporite

sedimentary rock formed from a deposit of precipitated minerals

Caused by the evaporation of salt water (desertification)

Hotter and drier climate

Latorite/Kaolinite

sedimentary rock formed from extreme weathering of parent rock

Requires hot temperatures and large amounts of water

Paleobiogeography

The distribution of fossils over space

Paleoclimatology

The reconstruction of climate through deep (geologic) time

This is a critical area of science in the climate change research

Plate tectonics theory

The "solid" earth is a thin crust that sits atop a semi-liquid asthenosphere

The earth is dynamic: energy is continually moving through the planet

Convection and other movement under the Earth's crust drives movement of the plates

It provides one line of evidence for continental drift
Largely rejected at first because it lacked a mechanism

Tillite

Sedimentary rock containing unsorted and unstratified rock material

Whole structure of rocks

Created by glacial deposition

If there's tillites, it means it was extremely cold and icy

Amniotes

(clade Amniota)

Greek: "amnion" = membrane surrounding the fetus

Two major clades of amniotes: Diapsida and Synapsida

Diapsids

Birds and reptiles

Have two holes behind the eye socket (postorbital fenestra)

Lystrosaurus

Greek: "lystro" = tool, shovel; "saurus" = lizard

255-250 Ma (million years ago), ~3ft long

A survivor from a once-dominant group of synapsids

Primary terrestrial fossil for ~10 million years

Mass extinction

an unusually large number of extinctions occurring worldwide

Pangea

the major paleocontinent at the start of the Mesozoic

Permo-Triassic mass extinction

Things going extinct for a million years, long duration

Worst mass extinction event the world has ever seen

Also known as the "Great Dying"

Up to 95% of marine species and 80% of land animals perished

Siberian traps

a huge deposit of igneous rock

~3 million square miles of basaltic rock, with eruptions continuing for ~2 million years

Synapsids

Mammals

Have one hole behind eye socket (postorbital fenestra)

Dominate the Permian

Crurotarsi

Latin: "cruro" = lower leg; "tarsi" = ankle

Includes the living crocodilians and their extinct relatives

Also known as clade Pseudosuchia

Synapomorphy: the crocodilian-type ankle (astragalus/calcaneum hinge)

Flat-footed, doesn't walk on its toes

Ectotherm

("cold blooded"): use external sources of energy to control their body temperature (requires more energy)

Outside temperature rises, body temperature rises

Outside temperature lowers, body temperature lowers

If there's a lot of predators around, those predators are likely ectothermic as they need less prey to survive

Effigia

Effigia okeeffeae

Latin: "effigia" = ghost; "okeeffeae" = in honour of Georgia O'Keefe for her paintings of the badlands at Ghost Ranch

~7ft long, lived at the end of the Triassic

Runs around on two legs

An impressive form of convergent evolution

Crurotarsi

Eoraptor

Greek: "Eo" = dawn; "raptor" = thief

~231-228 Ma, one of the oldest known dinosaurs

~3.5ft long

Serrated teeth in upper jaw and leaf-shaped teeth in lower jaw

Likely omnivore

May be more closely related to sauropods (long-necked dinosaurs) than theropods (meat-eating dinosaurs)

Early middle of Triassic period (very old)

Its anatomy gives us insight into what the first dinosaurs looked like (the ancestral condition)

Small, human size or smaller

Long tail

Walks on two legs

All dinosaurs come from Eoraptor

Endotherm

("warm blooded"): use metabolic processes to control their body temperature

Need more food than ectotherms, need more energy to constantly regulate body temperature

If there's not a lot of predators around, those predators are likely endothermic, as they need more prey to live

Pterosauria

a clade of extinct flying diapsids that existed during the Mesozoic

A strong wing supported by a single, elongated fourth finger

Flight requires a fast metabolism, which encourages the evolution of a filamentous coat

Pterosaur pycnofibers (filamentous coat) are commonly cited as an example of convergent evolution with mammalian fur, covered in fuzz/fluff

Reach enormous sizes in Cretaceous to try and outcompete birds

Ancestral trait

A characteristic that appeared in common ancestors

Coelophysis

Greek: "ceolo" = hollow, "physis" = process/form

~221-196 My

One of the earliest definitive theropods

Rapid rate of growth (larger than a similar sized reptile)

High variation in final adult size (variable rate of growth)

Bone bed in The Ghost Ranch in New Mexico

Pack behavior

Derived trait

a trait that differs from the ancestral trait

Plateosaurus

Greek: "plateo" = broad; "saurus" = lizard

~214-204 Ma

A bipedal herbivore

One of the earliest definitive prosauropods

Ancestral traits: Bipedal posture, Five digit hands

Derived traits: 10 caudal vertebrae, Leaf shaped teeth

Sauropodopmorphs/Sauropods

Greek: "sauro" = lizard; "pod" = foot

The largest dinosaurs

Notable for their long necks, which contained 10+ vertebrae

the long-necked plant eaters

Theropods

Greek: "theros" = wild beast; "pod" = foot

Some of the most morphologically diverse

Nearly all extinct species are meat eaters

Includes the birds

Flattened, serrated teeth

Ancestrally carnivores, although different clades evolve to specialize on other diets

Hollow bones

Four fingers or less on each hand

Cannot pronate arms, palms face inward towards each other

Bipedal, three toes on ground, one off

Evolve in Jurassic

Gondwana

Southern supercontinent

Laurasia

northern continent, includes Euramerica plus modern Asia

Lesothosaurus

"Lesotho" = A south African country; Greek: "saurus" = lizard

Found in the Karoo supergroup of Africa

Leaf shaped teeth, large eyes

Plant eater, ornithischians

Ornithiscia

Greek: "ornith" = bird; "ischia" = hip

Unlike the theropods and sauropods, definitive ornithischians do not appear until the Jurassic

Morphologically diverse plant eaters

Birds are NOT a part of this group!

Backwards pointing ischium and pubis bones in the pelvis (Theropods and Sauropods, ischium and pubis bones point in opposite directions)

Predentary bone in skull (which becomes a bony beak in many groups)

Several covered in filaments

Scutellosaurus

Greek: "scutello" = little-shielded; "saurus" = lizard

Found in Arizona

Short forelimbs and very long tail suggest it could walk on hind legs

Has scutes

Thyreophoran (body armor dino)

Allosaurus

Greek: "allos" = different; "saurus" = lizard

Allosaurus was the most common predator in the Morrison formation

~30 feet long

Strong skull and flexible jaw, but weak bite force

Tail vertebrae found with a partially healed puncture wound that fits a Stegosaurus tail spike, and a Stegosaurus neck plate with a wound consistent with Allosaurus bite

Would bite and then back off, let you bleed to death

Camptosaurus

Ancestor of hadrosaurs (duck billed dinos)

Ceratosaurus

Greek: "cerato" = horn; "saurus" = lizard

About half the size of Allosaurus

Notable for the elaborate horns over its nose and each eye

Dryosaurus

Ancestor of hadrosaurs

Ecology

the study of relationships among living organisms and their physical environment

Dinosaurs were dominant, but not isolated

Morrison Formation

A sequence of late Jurassic sedimentary rock (~156-147 Ma) found in the western United States & Canada

Relics of rivers and floodplains: evidence of wet/dry seasons

Rich in dinosaur fossils representing the three major clades (~40 genera total). Similar fossils found in the Lourinhã Formation in Portugal

Contains Camptosaurus, Dryosaurus, Allosaurus, Ceratosaurus, and Stegosaurus

Niche partitioning

a process where competing species use the environment differently in a way that helps them coexist

Not purposeful- the result of natural selection and competition

Allows for greater diversity

Ornithopods

Greek: "ornith" = bird, "pod" = foot

Characteristic three-toed feet

Traits: No armor, Horny beak, Elongated pubis, No hole in the lower jaw (no mandibular fenestrae)

Iguanodon

Predator/prey ratios

The predator/prey biomass ratio for the Morrison Formation as a whole is 8.6%. The values range from 5.1-11.9% at various stratigraphic levels

Lots of predators around = likely ectothermic, Need less prey to survive

Not a lot of predators around = likely endothermic, Need more prey to survive

Stegosaurus

Greek: "stego" = roof; "saurus" = lizard

Tail spikes for defense, function of plates is debated among paleontologists

Thyreophoran

Thyreophora

Greek: "thyreoph" = shield bearer

Traits: Body armor lined up in longitudinal rows along the dorsal portion of the body

Two major subclades: Ankylosauria and Stegosauria

Ankylosauria, Thyreophorans with bony osteoderms (modified scutes)

Stegosauria, Thyreophorans with spikes and plates as armor

Stegosauria go extinct, Ankylosauria dominates

Anchiornis

(~160 Mya) is known from hundreds of specimens in the Tiaojishan Formation, China

The wings, legs, and tail supported long but relatively narrow vaned feathers

"Near bird"

Gliding, limited flight

Birds

A clade of endothermic diapsids with feathers

The most successful group of flying vertebrates, with >9,000 species

What are its adaptations for flight? Hollow bones, Short tailbone, No teeth, Wings

Exaptation: use breathing system of theropods (air sacs and hollow bones) to make their bodies lighter

Diversify in Cretaceous

Brontosaurus

Greek: "bronto" = thunder; "saurus" = lizard

~70 feet long, 17 tons

Sauropod

Exaptations

When a trait that originally evolved for one purpose is reused to serve a new adaptive role

A good starting example is the breathing system of theropods, which utilized by birds over the course of evolution to make their bodies lighter (Air sacs inside the body for breathing then used for flight)

Feathers become an exaptation for display

Air sacs as an exaptation for sauropod necks, hydraulic necks, also allows sauropods to become huge

Pneumatic vertebrae

Vertebrae that are filled with air sacs

Exaptations of the hollow bones and air sac breathing seen in early dinosaurs like Eoraptor

Also allows extra oxygen, allows sauropods to become huge

Angiosperms

Plants that bear flowers and fruits

Weren't any flowering plants before Cretaceous

Way more effective at reproducing

Have seeds like gymnosperms, but use flowers and fruit for pollination and dispersal

Associated with diversification of insects in the fossil record: More pollinators, Different insects specializing on plants, Evolution of bees, ants, etc

Ankylosauria

Major subclade of thyreophorans

Thyreophorans with bony osteoderms (modified scutes)

Dominate after Stegosauria goes extinct

Tendons in the tail, So strong that they become preserved in the fossil, shows rigidity in the back of the tail, club at the end of tail

Very wide

Completely armored on the top/dorsal side

Ceratopsia

Greek: "cerato" = horned; "psia" = face

Horned dinosaurs (though early members lack horns)

Skin impressions show earlier, smaller species had a mixture of space and quills (feathers?); larger species only found with scales so far

Later species develop large, heavy skulls

Develop dental batteries like hadrosaurs (convergent evolution), New plants (angiosperms), need new teeth to get through them

Hadrosaurs/Hadrosaurids

Greek: "hadros" = stout, thick (better known as "duck billed dinosaurs"), Shape of their jaws

No defensive weapons, but many attained large sizes

Facultative bipeds, Could walk on four legs or two

Mummified skeletons reveals scaly skin and strong tendons in the tail, No flexibility in tail, No feathers

First group to provide evidence of nesting behavior

"Egg Mountain" in Montana preserved Maiasaura (Greek: good mother lizard) eggs in bowl-shaped nests; evidence of feeding

Are distinct from other ornithopods because of their complex dental battery, Dental battery: stacks of hundreds of teeth used for grinding plants

Marginocephalia

Latin: "margino" = margin; "cephalia" = head

The clade encompassing the last common ancestor of Ceratopsia and Pachycephalosauria

Noted for a "margin" of bone in the posterior portion of the skull, Shelf of bone on the back of their skull

Remarkable plasticity in bony margin allows for major changes in skull shape through life

Pachycephalosaurs

Bony, dome shaped head dinosaurs

Lots of evidence of cranial injury, Evidence that they are slamming their heads into something, perhaps other heads (like big-horned sheep)

Thyreophoran turnover

Stegosauria goes extinct, ankylosauria dominates

Phylogenetic bracketing

A method of inference used to infer the likelihood of unknown traits in organisms based on their position in a phylogenetic tree

How do we know velociraptor had feathers? Sits between Anchiornis and Archeopteryx in the phylogenetic tree, who both had feathers

Chicxulub crater

~110 miles in diameter and ~12 miles deep

Impact site linked to dino extinction