Fossils/Vertebrates

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Main article: Fossils

Superclass Agnatha (Jawless Fish) (Ostracoderms)

Agnatha.jpg
Physical Description They did not have jaws, paired fins, or a stomach. They have a notochord both in larvae and adults; and seven or more paired gill pouches. Their heart has two chambers.
Fossil Range Cambrian to recent.
Mode of Life/Habitat The Agnatha are ectothermic (cold blooded).
Distribution hey are distributed worldwide, except for the tropics and polar regions.
Taxonomy
Two groups remain today: the lampreys and the hagfish.

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.
Mode of Life/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"
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.


Genus Bothriolepis
Bothriolepis.jpg
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/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/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/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/Habitat Among the top marine predators


Genus Otodus
Otodus.jpg
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/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/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/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)

Actinopterygii.jpg
Physical Description They possess lepidotrichia or “fin rays.” Size ranges from 0.3in to 36 feet!
Fossil Range Late Silurian - recent
Mode of Life/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
Knightia.jpeg
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/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
Xiphactinus.jpg
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/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/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/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/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
Tiktaalik.jpg
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/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/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
Acanthostega.jpg
Physical Description 1 meter long. They had 8 fingers on each hand linked by webbing - no wrists.
Fossil Range Late Devonian
Mode of Life/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
Eryops.jpg
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/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/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/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/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


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/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/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)

Order Saurischia (lizard-hipped)

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Suborder Theropoda


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


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)

Infraorder Anklyosauria


Genus Anklyosaurus
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Infraorder Ceratopsia


Genus Triceratops
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Genus Protoceratops
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Infraorder Ornithopoda


Genus Iguanodon
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Genus Parasaurolophus
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Genus Maiasaura
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Infraorder Pachycephalosauria


Genus Dracorex
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Infraorder Stegosauria


Genus Stegosaurus
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Class Aves (Birds)


Genus Archaeopteryx
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)
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


Clade Synapsida

Mammal-like Reptiles


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/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)
Lystrosaurus.jpg
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/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)


Genus Basilosaurus (prehistoric whale)


Genus Equus (modern horse)


Genus Australopithecus (hominin)


Genus Homo (hominin)


Species H. neanderthalensis


Species H. erectus


Species H. sapiens


Genus Mammut (Mastodon)
Mammut.jpg
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/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/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)
Mprimigenius.jpg
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/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/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/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)
Smilodon.jpg
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/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.