Fossils/Vertebrates

Main article: Fossils

Subphylum Vertebrata

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Physical Description	Have a backbone and cranium.
Fossil Range	Evolved during the Cambrian Explosion.
Taxonomy	Kingdom: Animalia Phylum: Chordata
Adaptations Over Time	Slowly became bigger and more terrestrial. They evolved bigger jaws and stronger bones.

Superclass Agnatha (Jawless Fish) (Ostracoderms)

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Common Names	Jawless fish, including lampreys and hagfish.
Physical Description	They lack paired appendages and jaws. They have skin but no dermal or epidermal scales. Instead of stomachs, they simply have one long gut. Cold-blooded (ectothermic). Two-chambered heart. They have seven or more paired gill pouches. Possess a notochord (a cartilage-like rod that is a characteristic feature of all chordates in at least one stage of life) during their larval and adult stages. They possess a photoreceptive parietal eye for regulating circadian rhythm and body heat. The skeleton is made of cartilage.
Fossil Range	Cambrian Explosion to present-day.
Taxonomy	Agnatha is split up into Cyclostomata (extant and comprising lampreys and hagfish, ~120 species), Conodonta (extinct), and Ostracoderms (extinct). Sister taxon to Gnathostomata (jawed vertebrates). rRNA and mtDNA data suggest that Cyclostomata is monophyletic.
Mode of Life or Habitat	Cold marine waters from 10 meters deep at high latitudes to 1300 meters at low altitudes. Lampreys feed on other fish and mammals. Hagfish are scavengers. No known parental care, fertilization is most likely external.
Distribution	Worldwide, except for tropics and polar regions.
Etymology	Ancient Greek for "without jaws."
External Links	https://en.wikipedia.org/wiki/Notochord. https://en.wikipedia.org/wiki/Agnatha. https://en.wikipedia.org/wiki/Parietal_eye.

Class Placodermi (Armored Jawed Fish)

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Physical Description	Most were small fish reaching lengths of 15 cm; however, a few species reached lengths of 4 to 10 meters. They all have jaws, an internal skeleton, head and trunk armor, paired fins, and projecting spines to the sides of the trunk shield. A neck joint allowed them to lift the anterior portion of their head shield. They were the first vertebrates to evolve paired pelvic fins.
Fossil Range	They were among first jawed fish.
Taxonomy	Silurian to Devonian. They had the greatest diversity during the Devonian, aka the "Age of Fish." They became extinct at end-Devonian Hangenberg event.
Mode of Life or Habitat	Placoderms lived in both marine and freshwater environments. They were predators and some may have been filter feeders.
Additional Information	Placodermi means "tablet or plate skin"

Genus Bothriolepis

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Physical Description	About 60 cm to 1 meter long; average of 30 cm. Its dermal skeleton was organized in three layers: a superficial lamellar layer, a cancellous spongiosa, and a compact basal lamellar layer. The thoracic shield covered almost half of their body
Fossil Range	Middle and Late Devonian
Mode of Life or Habitat	It was a bottom-dweller inhabiting streams and lakevand found all over the world. Bothroolpis was not a pursuit predator with its small jaws and teeth and probably fed on bottom-dwelling invertebrate. It was a detrivore.
Adaptations Over Time	In addition to its gills, they had pouches that connected to the oesophagus, which may have been rudimentary lungs that may have allowed them to live for short periods out of the water.
Distribution	Northern Hemisphere
Additional Information	Its name means “trench scale”

Genus Dunkleostetus

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Physical Description	Measured up to 10 meters (33 ft.) and weighed 4 tons. Instead of teeth, they had 2 pairs of sharp plates which formed a beak.
Fossil Range	Late Devonian. It became extinct in the Hangenberg event.
Mode of Life or Habitat	Probably inhabited inshore waters, and may have been pelagic. It was the apex predator of its range. They were slow swimmers so they ambushed their prey to hunt.
Distribution	North America, Poland, Belgium, and Morocco
Additional Information	Dunkleosteus was named after David Dunkle "Dunkle + Osteus = Dunkle’s bone."

Class Chondrichthyes (Cartilaginous Fish)

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Physical Description	They were among the first vertebrates to evolve jaws and bony teeth. Their pectoral fins are fused on the top of their heads. They have skeletons primarily composed of bone tissue, as opposed to cartilage.
Fossil Range	Late Silurian to recent.
Mode of Life or Habitat	They were predators, with teeth well suited to molluscs and baculites. Some lived in freshwater in the Early Paleozoic but others lived in salt water.
Adaptations Over Time	They are a very diverse taxonomic group of fish.
Additional Information	Due to their lack of a swim bladder, they must continuously swim to avoid sinking.

Superorder Selachimorpha (Sharks)

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Physical Description	Their skeletons made of cartilage instead of bone. They shed and replaced their teeth and scales. They have Ampullae of Lorenzini in order to detect the electromagnetic fields produced by their prey.
Fossil Range	Silurian to recent.
Mode of Life or Habitat	Among the top marine predators

Genus Otodus

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Physical Description	The largest known teeth measure about 104 mm (4.1 in) in height. They at least reached 9.1 m (30 ft) in total length with a max length of 12.2 m (40 ft).
Fossil Range	Lower Paloecene to Middle Miocene.
Mode of Life or Habitat	They primarily ate other sharks.
Adaptations Over Time	Scientists determined it evolved into genus Carcharocles, given substantial fossil evidence in form of transitional teeth.
Additional Information	Otodus means “ear-shaped tooth”

Genus Carcharocles (formerly Carcharodon)

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Physical Description	Carcharocles is estimated to be 13 meters long - they are one of the world's largest predators. They have about 24 teeth in their upper jaw and 20 in their lower jaw.
Fossil Range	Early Eocene to Pliocene
Mode of Life or Habitat	They could be found in shallow coastal waters, swampy coastal lagoons, offshore deep water environments, etc. They are a transient species - they often move around.
Distribution	Found in North and South America, Africa, Europe, Japan, Australia and New Zealand.
Additional Information	In Greek, Carcharocles means "Famed for Jaggedness."

Species Carcharocles megalodon

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Physical Description	C. Megalodon was up to 18 m (59 ft) in length. Its skeleton was heavily calcified. They had about 276 teeth in 5 rows.
Fossil Range	Cenzoic era - Middle Miocene to end of Pliocene. Became extinct due to oceanic cooling, sea level drops, decline in food supply, and new competition.
Mode of Life or Habitat	Adults were not abundant in shallow water environments, and mostly lurked offshore. They gave birth to their young in shallow water environments. They preyed upon whales, porpoises, sea turtles, etc.
Additional Information	Megalodon means "big tooth" in Greek.

Superorder Batoidea (Rays)

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Common Names	Skates and Rays
Physical Description	They have flattened bodies with wing-like pectoral fins and whip-like tails. Their eyes are on top of their bodies with their gills under. They have heavy, rounded teeth for crushing the shells of prey.
Fossil Range	Early triassic
Taxonomy	Contains more than 500 species, and 13 families.

Class Actinopterygii (ray-finned)

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Physical Description	They possess lepidotrichia or “fin rays.” Size ranges from 0.3in to 36 feet!
Fossil Range	Late Silurian - recent
Mode of Life or Habitat	They feed on algae, diatoms, insects, and smaller fish. Freshwater and marine environment.
Adaptations Over Time	They were the first ever bony fish! The swim bladder evolved into a more efficient organ in the teleost making them neutrally buoyant.
Distribution	Remains have been found in Russia, Sweden, and Estonia
Additional Information	Actinopterygians are the dominant class of vertebrates, comprising nearly 99% of the over 30,000 species of fish. They account for half of living vertebrates

Genus Knightia

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Physical Description	Knightia has heavy scales and small, conical teeth. They were typically 3-5 inches long - the longest was Knightia eocaena which grew up to 10 inches long.
Fossil Range	Early Eocene.
Mode of Life or Habitat	Freshwater lakes and rivers. Ate small marine organisms like plankton, diatoms, algae, etc. They travelled in large schools. Were an abundant food source for larger predators.
Distribution	North America and Asia
Additional Information	Knightia is the state fossil of Wyoming - they are abundant in the Green River formation. They are the most commonly excavated fish in the world!

Genus Xiphactinus

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Common Names	"Bulldog fish"
Physical Description	The tail is forked, and attached to a narrow base. At 25-30 feet long, it was the largest bony fish of the Cretaceous. The jaw is very mobile, and therefore able to take in large prey.
Fossil Range	Cretaceous. They became extinct due to the Cretaceous-Paleogene extinction.
Mode of Life or Habitat	Shallow and deep marine. They ate fish, seabirds, and maybe pterosaurs.
Additional Information	Their name comes from the Latin & Greek for “sword ray.” State fossil of Kansas.

Class Sarcopterygii (lobe-finned)

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Physical Description	Their fins differ from those of all other fish - each is on a fleshy, lobelike stalk extending from the body.
Fossil Range	Late Silurian to recent.
Mode of Life or Habitat	They live in a combination of aquatic and terrestrial environments, hibernating while on land. They are ovoviviparous, and they have lungs and gills.

Genus Eusthenopteron

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Common Names	Fish with Legs.
Physical Description	They were 5-6 feet long, and covered in scaly skin.
Fossil Range	Late Devonian
Mode of Life or Habitat	They lived in shallow waterways, and preyed on smaller fish.
Adaptations Over Time	They have a close relationship to tetrapods.
Additional Information	The name means “strongly developed fins” (Greek).

Genus Latimeria (Coelacanth)

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Physical Description	They are 200cm long and weigh 80 kg.
Fossil Range	Middle Pleistocene to recent.
Mode of Life or Habitat	They are found in deep reefs and volcanic slopes - both freshwater and marine environments.
Additional Information	The name is from the Greek words "koilos" meaning “hollow” and "akantha" meaning “spine.” They live very long - possibly up to 80-100 years! They are one of the most endangered genus of animals in the world.

Genus Tiktaalik

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Physical Description	3 to 9 feet long. The eyes were on the top of the skull, rather than the sides. The shoulders were not connected to the skull, so it had a functional neck.
Fossil Range	Late Devonian
Mode of Life or Habitat	They ate smaller fish and bug-like creatures. It is unlikely that they could live entirely on land.
Adaptations Over Time	They were an extremely important transitional form between fish and tetrapods.
Additional Information	There is only one species: Tiktaalik rosae. "Tiktaalik" means "large freshwater fish" (Inuktitut language)

Class Amphibia (Amphibians)

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Physical Description	Changes in anatomy allowed the upper body to be propped up for breathing, the head to turn, and created a rigid structure strong enough to support walking. Their eyes are larger than their predecessors because eyesight is more important on land than in water. They can weigh up to 500 pounds.
Fossil Range	Devonian to recent.
Mode of Life or Habitat	Marine and terrestrial. Carnivorous.
Adaptations Over Time	They may have moved to land because of seasonal droughts and escape from drying pools, or maybe because they were carnivores and the land had a lot of arthropods which they could eat.
Additional Information	"Amphibia" means “double life” and refers to a life cycle that includes an aquatic existence and a terrestrial existence.

Genus Acanthostega

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Physical Description	1 meter long. They had 8 fingers on each hand linked by webbing - no wrists.
Fossil Range	Late Devonian
Mode of Life or Habitat	Shallow, weed-choked swamps.
Adaptations Over Time	In general, they were pretty poorly adapted for going on land (for example, joints weren't very mobile, shoulder and forearm were very fish-like, ribs were too short to support chest out of water).
Additional Information	The name means "spiny roof."

Genus Eryops

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Physical Description	Usually 1.5 - 2 meters long, but could grow up to 3 meters long, making them some of the largest land animals of their time. Average mass was 90 kg. They had an unusually large skull and mouth, with many teeth. The shoulder girdle is disconnected from the skull for improved terrestrial locomotion.
Fossil Range	Mainly Permian - appeared in the Pennslvanian epoch.
Mode of Life or Habitat	Predator - large fish and aquatic tetrapods. Habitat was lowland habitats in and around ponds, streams, and rivers - juveniles probably lived in swamps which gave them protection from predators, while adults spent most of their time on land.
Distribution	Southwestern United States.
Additional Information	Name means "drawn-out face."

Genus Diplocaulus

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Physical Description	Up to 1 meter in length. They had a distinct boomerang-shaped head. Skulls are up to 16 inches wide across the horn tips. Their mouth gape was very small because the lower jaw hinge was posterior to the eye sockets.
Fossil Range	Late Permian.
Mode of Life or Habitat	Rivers, lakes, swamps. They ate insects and fish.
Adaptations Over Time	Their head shape could have been defensive because predators would have a hard time trying to swallow such a large head.
Distribution	North America and North Africa.
Additional Information	Name means "double caul."

Class Reptilia (Reptiles)

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Physical Description	They range from 17 mm to 6 m in length. They have a 3-chambered heart with 2 atria, 1 ventricle, and 2 aortas. They use lungs to breathe. Their skin is rather thin so it is often covered in scales.
Fossil Range	Pennsylvanian to recent. They were dominant during the late Paleozoic and Mesozoic.
Mode of Life or Habitat	They are oviparous, and they shed their skin continuously throughout their lifetimes. Most are insectivorous or carnivorous

Order Crocodilia (crocodiles)

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Order Testudines (turtles)

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Order Icthyosauria (Ichthyosaurs)

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Physical Description	Usually around 2-4 meters in length. They could swim at speeds up to 25 mph. They have the largest known eyes of any reptile.
Fossil Range	Early Triassic to Late Cretaceous. They were the most abundant in the late Triassic and early Jurassic.
Mode of Life or Habitat	Carnivorous, viviparous. Sight was their main sense, and their hearing may have been poor.
Distribution	All Mesozoic oceans - Europe and Asia.
Additional Information	Their name means "fish lizard."

Order Squamata

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Family Mosasauridae (Mosasaurs)

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Physical Description	They were anywhere from 2.5 to 17 meters long. Their jaws were double-hinged and flexible, so they would often gulp down their prey whole. They had an expanded chest region, suggesting that they had 2 lungs.
Fossil Range	Late Cretaceous
Mode of Life or Habitat	Warm, shallow seas. They were dominant marine predators. They were viviparous.
Distribution	Worldwide.
Additional Information	They are probably related to snakes due to similarities in their jaws and skulls.

Order Plesiosauria (Plesiosaurs & Pliosaurs)

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Physical Description	They were anywhere from 3 to 20 meters long. They had a broad, flat body and a short tail. Their necks had up to 70 vertebrae. Plesiosaurs had long necks, small heads, and were slow, while pliosaurs had shorter necks, large heads, and were apex predators. They had a euryapsid skull.
Fossil Range	Late Triassic - Late Cretaceous. Became extinct in the Cretaceous-Paleogene extinction event.
Mode of Life or Habitat	Oceanic environment. Plesiosaurs ate fish and cephalopods. Pliosaurs ate fish, cephalopods, sharks, ichthyosaurs, and even plesiosaurs.
Adaptations Over Time	They have two main morphs - plesiosaurs and pliosaurs.
Distribution	Worldwide
Additional Information	Their name comes from the Greek "plesios" meaning "near to" and "sauros" meaning "lizard."

Order Pterosauria (Pterosaurs)

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Clade Dinosauria (Dinosaurs)

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Order Saurischia (lizard-hipped)

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Suborder Theropoda

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Genus Allosaurus

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Genus Coelophysis

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Genus Dilophosaurus

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Genus Spinosaurus

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Genus Tyrannosaurus

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Genus Velociraptor

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Suborder Sauropodamorpha

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Genus Brachiosaurus

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Genus Diplodocus

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Genus Patagotitan

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Genus Plateosaurus

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Order Ornithischia (bird-hipped)

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Infraorder Anklyosauria

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Genus Anklyosaurus

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Infraorder Ceratopsia

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Genus Triceratops

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Genus Protoceratops

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Infraorder Ornithopoda

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Genus Iguanodon

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Genus Parasaurolophus

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Genus Maiasaura

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Infraorder Pachycephalosauria

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Genus Dracorex

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Infraorder Stegosauria

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Genus Stegosaurus

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Class Aves (Birds)

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Genus Archaeopteryx

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Physical Description	A feathered dinosaur that could be the size of a bluejay to a chicken. Looked similar to a theropod other than the fact that it had feathers.
Fossil Range	Late Jurassic
Distribution	Europe

Genus Titanis (Terror Bird)

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Physical Description	Large flightless carnivore bird. It could reach heights of about 2.5 meters and usually weighed around 150kg. It can most easily be recognized by its large skull and hooked beak.
Fossil Range	Pliocene-Early Pleistocene
Distribution	North America

Genus Icthyornis

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Clade Synapsida

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Mammal-like Reptiles

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Genus Dimetrodon (pelycosaurs)

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Physical Description	They grew up to 3.5 meters long. They have 2 types of teeth - shearing teeth and canine teeth. They have a sail supported by spines sprouting from the vertebrates.
Fossil Range	Permian to Cisuralian.
Mode of Life or Habitat	They were an apex predator.
Adaptations Over Time	Their sail had many uses, such as thermoregulation, sexual display, looking larger to predators, and stabilization of the spine.
Distribution	Mainly Southwestern US, but also Europe.
Additional Information	"Dimetrodon" means “2 measures teeth.”

Genus Lystrosaurus (therapsids)

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Physical Description	About 3 feet long. They don't have any teeth besides the tusk-like upper canines. They had huge forearms - thought to be a powerful burrower.
Fossil Range	Late Permian to Early Triassic.
Mode of Life or Habitat	Desert-like landscape. They were herbivores, and ate plants and roots.
Adaptations Over Time	They survived the Permian-Triassic extinction event.
Distribution	Mainly Africa.
Additional Information	"Lystrosaurus" means "shovel lizard." For a while, 95% of all land vertebrates were Lystrosaurus. They are good index fossils.

Class Mammalia (Mammals)

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Genus Basilosaurus (prehistoric whale)

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Genus Equus (modern horse)

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Genus Australopithecus (hominin)

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Genus Homo (hominin)

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Species H. neanderthalensis

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Species H. erectus

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Species H. sapiens

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Genus Mammut (Mastodon)

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Physical Description	Usually around 2.3 meters tall at the shoulders. Could weigh up to 4.5 tons. They had low-crowned or “bunodont” cheek teeth covered in thick enamel. They had 2 or 3 teeth in each half of the jaw.
Fossil Range	Late Miocene-Late Pleistocene
Mode of Life or Habitat	They lived in forests. Their social groups consisted of females and young, while the males abandoned the mixed herds once reaching sexual maturity and lived either alone or in male bond groupings. They mainly ate trees and shrubs.
Distribution	North and Central America, less common in Africa and Eurasia
Additional Information	Their name means “nipple tooth.”

Genus Mammuthus (Mammoth)

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Physical Description	About as large as a modern Asian elephant - 2.5 - 3 meters tall at the shoulder. The teeth consisted of a series of plates surrounding a dentine core. They were held together in a matrix of dental cement.
Fossil Range	Early Pliocene-Early Holocene
Mode of Life or Habitat	They ate grasses, fruits, shrubs, etc. Baby mammoths ate the dung of the adults.
Distribution	North America, Eurasia.
Additional Information	The name means “earth” from the Tartar word “mamma.”

Species M. primigenius (Wooly Mammoth)

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Physical Description	About the same size as modern African elephants - shoulder height 2.6 - 3.4 meters. They had 4 functional molars at a time. The tusks in males were usually around 2.5 meters long and weighed 45 kg, while in females they were only about 1.5 meters and weighed around 9 kg. They had an outer layer of long hair which was up to 90 cm long. They also had a denser, shorter inner layer of hair.
Fossil Range	Middle Pleistocene to Early Holocene. They became extinct due to climate change or hunting.
Mode of Life or Habitat	Grasses, herbaceous plants, flowering plants, shrubs, etc. Adults needed to eat 6 tons of food daily! They lived in matriarchal family groups.
Adaptations Over Time	They were well adapted to the cold environment of the last ice age - thick layer of fat, fur, small ears (to minimize frostbite), etc.
Distribution	Northern Eurasia and North America.
Additional Information	Their name means "first elephant" in Latin. State fossil of Alaska, Nebraska, and Vermont

Genus Megacerops (Brontothere)

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Physical Description	Up to 5 meters tall. They had an odd number of toes. The dorsal vertebrae above the shoulders had long spines to support the huge neck muscles needed to carry the heavy skull. They had a pair of blunt horns on their snout.
Fossil Range	Late Eocene
Mode of Life or Habitat	The shape of its teeth suggests that it preferred food such as soft stems and leaves, rather than tough vegetation. Adults may have used their horns to defend themselves and their calves from predators.
Distribution	North America
Additional Information	Name means "large-horned face." Closely related to Mesohippus.

Genus Mesohippus (three-toed horse)

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Physical Description	They were about 60 cm tall, 4 feet long, and weighed about 75 pounds. They had three toes.
Fossil Range	Middle Eocene to Early Oligocen
Mode of Life or Habitat	They were herbivores, although their teeth were unsuited to grazing (this trait was adopted in later, more advanced horses)
Adaptations Over Time	Longer legs and longer/larger face than earlier equids. They were faster than earlier horses. They were the first of the three-toed horses.
Distribution	North America
Additional Information	In Greek, "meso" means “middle” and "hippos" means “horse.”

Genus Smilodon (saber-toothed cat)

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Physical Description	They weighed up to 400 kg. Their teeth were about 7 inches long and their upper canines were more than 10 inches long. Teeth were fragile, and they had a weaker bite than other big cats. They had a hyoid bone to help them roar. They had shorter but more massive limbs than other felines.
Fossil Range	Pleistocene
Mode of Life or Habitat	They were carnivores - ate bison, elk, deer, etc. They may have lived in social groups. Canines may have been an attraction during mating.
Distribution	North and South America
Additional Information	In Greek, "smile" means “chisel” and "odous" means “tooth.” There are hundreds of Smilodon fossils in the La Brea Tar Pits.