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84 Cards in this Set
- Front
- Back
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When did tetrapods evolve? |
Devonian (416-360mya) |
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Name the two important Devonian stem tetrapods |
Ichthyostega and acanthostega |
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What's surprising about ichthyostega and acanthostega? |
Polydactyly. Also, had limbs but we're clearly aquatic |
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What are tetrapodamorph fish (fishapods)? |
Sister taxa to tetrapods, within Tetrapodamorpha |
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Which 8 characteristic tetrapod features did the Devonian stem tetrapods possess? |
Choanae; stapes; neck; limbs; digits; laterally facing glenoid; large pelvic girdle; enlarged ribs. |
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Which key character of tetrapods evolved first? |
Choanae- in tetrapodamorph fish |
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Which fossil showed first tetrapodamorph fish with neck? |
Tiktaalik |
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What evolved after the choanae and neck? |
Large spiracular notch- may have permitted air breathing |
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Describe the girdles of tetrapodamorph fish |
Larger front than back |
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Describe the girdles of modern tetrapods |
Large pelvic girdle, smaller pectoral girdles |
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Between which two fossils did the transition from front-wheel drive to rear-wheel drive evolve? |
Panderichthys and Acanthostega |
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Which fossil showd the beginning of the trend from front-wheel to rear-wheel drive? |
Tiktaalik |
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What was next to evolve, after rear-wheel drive? |
Homologues of major limb bones, as seen in Panderichthys |
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How did the ear originate? |
As a breathing apparatus |
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When did the tetrapods invade land? |
The carboniferous |
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What was Romer's gap? |
Gap in fossil record spanning the first 15my of the carboniferous. |
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What came before Romer's gap? |
Tetrapodamorph fish- aquatic, stem group tetrapods. |
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What came after Romer's gap? |
Tetrapods, with all characters primitive to crown group tetrapoda |
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When did the 'paleozoic' amphibia evolve? |
Late (upper) Carboniferous |
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What were the two great groups of palaeozoic amphibia? |
Temnospondyli and Lepospndyli |
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What is included in the reptile grade? |
Non-avian, non-mammalian amniotes |
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When do the first amniote fossils emerge? |
Upper Carboniferous |
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What are the 3 derived characters of crown group amniotes? |
Amniotic egg; keratinized skin; venting by negative pressure aspiration pump |
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What are the 4 extraembryonic membranes found in the amniotic egg? |
Amnion, allantois, chorion, yolk sac. |
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What does the amnion do, and where is it? |
Forms amniotic cavity around the embryo, cushioning it in a buffered aqueous environment |
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Allantois |
Outgrowth of gut. Forms sac to store nitrogenous waste and exchange gas. |
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Chorion |
Envelopes interior of egg. Joins allantois to form the chorio-allantoic membrane- for gas exchange |
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What were the 3 adaptive scenarios suggested for the origin of the amniotic egg? |
Competing the transition to dry land; increased egg and hence body size on land; extended embryonic retention |
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What is B-keratin? |
Very tough, only in sauropsida, claws, feathers, scales etc. |
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What is the thick, cornified outer layer of amniotes called? |
Stratum corneum |
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What's the primary ventilation method in amniotes? |
Negative-pressure aspiration pump |
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What do snake's use in chemosensation |
Forked tongue and vomeronasal organs |
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What do pit vipers use? |
Pit organs- infrared sensors can detect change in temperature of 3/1000s of a degree |
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How does the Namib desert viper collect water? |
Flattens its body and collects dew, which it then licks off of itself. |
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Name an example of an anapsid amniote family |
Mesosauridae |
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When did Mesosauridae evolve? |
Lower permian |
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Describe Mesosauridae |
Small (up to 2m), marine reptiles, sieved crustacea or fish, possibly viviparous. |
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What's the defining feature of diapsids? |
Upper and lower temporal fenestrae |
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What does diapsida include? |
Extant reptiles and birds, plus many extinct forms |
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Name an example of a diapsid showing the 'ancestral condition' |
Testudines |
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How is the testudine skull explained? |
Ancestor had anapsid skull, evolved diapsid skull, secondarily evolved anapsid condition |
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What are the two main groups in the testudines? |
Pleurodira and Cryptodira |
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Feature of Pleurodira |
Retract neck sideways |
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Feature of Cryptodira |
Retract head vertically |
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What percentage of all extant reptiles is made up by the lepidosaurs? |
95%- includes lizards, snakes and tuatara |
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Are squamates ever viviparous? |
Yes, viviparity has evolved over 100 times |
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How many chambers in the crocodile and bird hearts? |
4 |
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Which groups are included in Archosauria? |
Pterosaurs, crocodiles and dinosaurs |
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In Pterosauria, what are pycnofibres? |
Hair-like integumentary appendages |
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What are actinofibrils? |
Structural filaments in wing membrane. Achieving appropriate directional strength to confer good shape for flight |
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Two main dinosaur groups |
Ornithischia and Saurischia |
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What are the Ornithischia? |
Herbivorous bipeds and quadrupeds |
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What are the Saurischia? |
Long-necked herbivorous dinosaurs, and bipedal predators (including birds) |
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Name an Ornithischian dinosaur |
Stegosaurus |
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Name a Saurischian dinosaur/group |
Theropoda- velociraptor and birds |
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When did dinosaurs evolve, and when did they hit peak diversity? |
Evolved middle Triassic, diversified slowly in Triassic, peaked in Cretaceous |
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When did dinosaurs evolve? |
Cretaceous-paleogene or K-Pg boundary |
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What happened 66mya? |
Extraterrestrial impact struck gulf of Mexico |
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2 other factors in dinosaur demise |
Volcanism- opening of Deccan Traps in India (late Cretaceous). Global marine regression- every of the 5 mass extinctions was proceeded by fall in sea level. |
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First bird fossils? |
Late Jurassic, 150mya |
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When was main aviation radiation? |
65-50 mya? |
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What are paleognathae? |
Ostriches, rhea, cassowary, emu, kiwi |
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3 colour pigments of feathers |
Melanins, carotenoids, porphyrins |
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Name a bird which migrates seasonally in response to productivity |
Common cuckoo, thrush nightingale, red-backed shrike |
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Bird showing leapfrog migration? |
Swallow in Europe |
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What's special about the willow warbler migration? |
It's split between SW Europe and SE Europe. Relic of species existing in two refugia during the last glaciation? |
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What's special about the wheatear migration? |
Non-adaptive- Two routes to Africa from South and West North America, 18,000 and 11,000km respectively. Two separate colonisations |
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What is an Emlen funnel? |
Thing to put a bird in- direction of hopping indicates migratory pathway |
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When did the Therapsids evolve? |
Early permian |
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List the big 7 evolutionary trends in synapsids |
Larger temporal fenestra, greater teeth specialisation, boney secondary palate, limb positioning, dual hair locomotion, loss of lumbar ribs suggests diaphragm, better homeostasis. |
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Features of Mesozoic mammals? |
Small. Skull features suggest big brain and inner ear. Lactation and suckling-unseasonal breeding. Hair. Hadrian gland. |
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Modern mammal characteristics |
Endothermy, reproduction, lactation, hair, advanced locomotion, improved sensory systems, high BP etc. |
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What is polyphyodonty? |
Having multiple regenerations of teeth |
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What is the mammalian tooth condition? |
Diphyodonty |
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What is occlusion? (Context of teeth) |
Allignment of top and bottom teeth |
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4 uses of vibrissae? |
Communication, insulation, sensory, camouflage |
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What do platypuses use to detect electric fields? |
Ampullae |
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Purpose of masseter? |
Puts closing force on the back teeth |
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Purpose of temporalis? |
Puts closing force on the front teeth |
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Purpose of pterygoid |
Closes jaw and stabilises mandible |
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Purpose of digastric muscle? |
Opens jaw |
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What does hypselodont mean? |
Having teeth with long crown and short root |
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When was the initial radiation of he apes across Eurasia? |
Middle Miocene. Monkeys suffered |
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What happened to apes in the late Miocene/Pliocene? |
They suffered to benefit of monkeys. One species came down from the trees. |
