Livet (Mesozoic) Flashcards
How did life do after the great dying?
A few labyrinthodont amphibians survived the Permian
extinction (stor padde krokodille lignende bæst)
Marine bivalves, gastropods, and cephalopods (blæksprutter) rebounded
strongly after the end Permian mass extinction
Forklar de generrelle træk ved mesozoikum, og inkluder keywords, som Angiosperms (flower plants), reptile
Triassic Period (252 to 201 million years ago):
Climate: The early Triassic was marked by a relatively hot and arid climate, but it became more humid as the period progressed.
Life: Reptiles, including the first dinosaurs, began to diversify. Mammals also appeared but remained small and relatively insignificant.
Jurassic Period (201 to 145 million years ago):
Climate: Generally, the climate was warmer and more stable than in the Triassic.
Life: Dinosaurs continued to dominate the terrestrial ecosystems, with iconic species like the giant sauropods and theropods. The first birds and mammals continued to evolve.
Cretaceous Period (145 to 66 million years ago):
Climate: The climate remained warm, and sea levels were high.
Life: Dinosaurs continued to flourish. Flowering plants (angiosperms) diversified, and new types of dinosaurs, such as the duck-billed dinosaurs and horned dinosaurs, emerged. Birds and mammals underwent further evolution.
Keywords:
Angiosperms
dinosauros
Duckbilled, and horned dinosaurs.
Describe the evolution from Archosaurs
Ornithodira: Archosaurs are divided into two main branches: the Pseudosuchia (crocodile-line archosaurs) and the Ornithodira (bird-line archosaurs). Ornithodira includes dinosaurs and pterosaurs.
Dinosauria:
Dinosaurs, a subgroup within the Ornithodira, were a diverse group of animals that dominated terrestrial ecosystems for millions of years.
Dinosaurs are further divided into two main groups: Saurischia (lizard-hipped dinosaurs) and Ornithischia (bird-hipped dinosaurs).
Pterosaurs:
Pterosaurs were flying reptiles that lived during the Mesozoic Era alongside dinosaurs. They are not dinosaurs but are part of the archosaur group.
Pterosaurs had a unique wing structure, with a membrane of skin stretched between an elongated fourth finger and the body.
Crocodile-Line Archosaurs (Pseudosuchia):
This group includes crocodilians, which are the only living representatives of the pseudosuchians.
Pseudosuchians were diverse during the Mesozoic, and some had body forms similar to modern crocodiles, while others were more adapted to terrestrial or bipedal locomotion.
Birds (Avialae):
Birds evolved from a group of small, feathered theropod dinosaurs during the Jurassic period.
Birds are characterized by feathers, a beak, a lightweight skeleton, and a high metabolic rate.
Med egne ord:
Reptiler dominerer, mammals linje adskiller sig med therapsiths, tetrapod like dyr, som er hurtigere og ny kæbe klasse imellem mammals og reptiler. Fra reptiler udskiller sig en gruppe af archosaurs ikke dinosaur, men var bipedal, og dommerende, derfra udviklede crocodilelinje og ornithodira. Fra Ornithidira kom Pterosaurs som var en flyvende øgle (minus fjer for ikke fugle linje), og dinosauros (birdline). Fra dinosauros kom Ornithischia Birdlike pelvis (bækken), og Saurischia lizard like pelvis. Ornithischia var mest mangfoldig. Fra saurischian kom Sauropod (langhals) og Theropod (birdline) (T-Rex).
Saurischians were mostly very large, quadrupedal herbivores that traveled in herds
Sauropods
Mostly very large, quadrupedal herbivores that traveled in herds.
Theropods
were bipedal, mostly carnivorous, and some even had feathers… …
modern birds ARE their descendants.
Hvad hed den første dino med bird skeleton? and when?
Around 150 MA ago, Archaeopteryx
Hvem overlevede the cretaceous extinction
Survivors of Cretaceous extinction:
Crocodiles freshwater predator by Jurassic
Turtles first evolved in the Triassic
Lizards are known from at least the Late Permian
Snakes appeared in the Cretaceous
Some marine life? in Mesozoikum?
Cephalopods (ammonites), gastropods, and brachiopods
How did mammals evolve? and when
Evolved in late triassic, Mostly small.
Therapsiths, tetrapod like dyr, som er hurtigere og ny kæbe. Klasse imellem mammals og reptiler.
Divergated in late jurassic:
- Monotremes - egg laying,
- marsupials pouched birth and placentals (live birth)
Chance en ear bones, and jaw bones.
1) What were some key environmental characteristics of the Mesozoic?
Somewhat stable, warm. Good for evolution.
2) How did the Creataeous get its name?
Limestone. Chalk sediments.
3) What do you know about feather evolution? Who? Why?
It started as more scattered and not so thickly packed feathers. These could have been used for non-flying purposes such as attracting a mate, providing shelter for their younglings, camouflage like purposes we know of today. The feathers certainly could bear the animals in the air at the beginning. This might have taken 50 million years to develop (Early Jurassic or Late Triassic). Maybe as a result of the dinosaurs flapping their arms when running uphill to gain momentum.
4) What is the evidence that dinosaurs were warm blooded?
Two main types of thermoregulation in vertebrates:
Ectothermy (cold-blooded): can’t generate own heat - Reptiles
Endothermy (warm-blooded): can generate own heat - Mammals and birds
Numerous passageways in bones similar to living endotherms than ectotherms
But there are exceptions like crocodiles and turtles so scientists disagree
Small population percentage compared to their prey
Because due to endotherms metabolism endothermic predators must eat more - therefore there must constitute a much smaller proportion of the total animal population compared with their prey, usually only a few percent. In contrast, the proportion of ectothermic predators to prey may be as high as 50%. Where data are sufficient to allow an estimate, dinosaur predators made up 3–5% of the total population. Nevertheless, uncertainties in the data make this argument less than convincing for many paleontologists.
Large brain in relation to body size
A larger brain requires a more constant body temperature. Because some dinosaurs seem to have been quite smart - especially up to medium size theropods
Some dinosaurs had feathers
Evidence for theropod endothermy comes from their relationship to birds
Today, only endotherms have hair, fur, or feathers for insulation.
Four-chambered heart
Similar to today’s mammals and birds
Large body size enables heat to be retained more effectively
Because the surface area where heat loss can take place is relatively small compared to the volume of the body size of larger animals.
The large sauropods were probably not endothermic, but nevertheless were capable of maintaining a rather constant body temperature.
5) Did mass extinctions hurt or help biodiversity in the long run?
It does help new groups of animals to diversify. For example, after the extinction of the dinosaurs, mammals now had the opportunity to fill out the gap, replacing the dinosaurs with themselves in the empty ecosystems. Not sure if it exactly helps the biodiversity but it sets the ground for changes. But still wipes out great numbers of other families.
6) What was the general timeline of Mesozoic mammal evolution?
THERAPSIDS (Permian) TO CYNODONTS TO MAMMALS (late Triassic)
Fossils prove as evidence for the transition from Cynodonts to mammals. The most notable changes take place in the jaw and the ear. During the transition from cynodonts to mammals, the quadrate and articular bones that had formed the joint between the jaw and skull in reptiles were modified into the incus and malleus of the mammalian middle ear.
Jaw bones of the reptile was transformed into ear bones in the mammals
7) What do supercontinents have to do with mass extinctions?
The forming and breakup of a super continent can have a big impact on the climate. Collisions makes mountains, which can be weathered favoring calcium carbonate precipitation in the oceans leading to further drawdown of CO2 from the atmosphere to the ocean. Over time temperature eventually drops creating ice sheets with a positive feedback of the albedo creating even more ice. If the supercontinent is located close to a pole, larger ice sheets can form, again increasing feedback effects. They can also stop the distribution of warm oceanic currents along equator.
In reverse, when a supercontinent is breaking up due to rifting, ocean currents are opened up for again, volcanic activity increases CO2 levels, ice melts and decreases albedo. All making the temperature rise.
Therefore the making or breaking of a supercontinent can affect the climate and wipeout species more or less dependent of a stabilized climate.
Can you split pangea into two “groups”
Laurasia and Gondwana
