Munch’s Mass Flow or Pressure Flow Hypothesis:.

There is speculation that dinosaurs flowering plants in a coevolutionary dance, as low-browsing ornithischians put pressure on plants to grow and reproduce quickly, and angiosperms are far more effective at those activities than all plants preceding them. The spread of angiosperms in the mid-Cretaceous coincided with the ornithischians’ rising dominance, and by the end-Cretaceous extinction, they were the most numerous herbivores by far. appeared in the late Jurassic and went extinct by the late Cretaceous.

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Mass-flow or pressure-flow hypothesis: How do organisms ‘solve’ common problems?

25-4-2016 · Mass Flow Hypothesis.

The Triassic began hot and ended hot, and the Jurassic and Cretaceous were also hot, so staying warm was not a significant issue for dinosaurs. stayed cool by becoming aquatic, and for land-based dinosaurs, features such as plates apparently replaced the sails of for both heating and cooling, and like the synapsid sail, those plates may have also been used for display. Also, like the cliché, many large herbivorous dinosaurs lived near cooling swamps, although the issue has been controversial. Cooling swamps and protective water holes that we see in the tropics today were a major aspect of Mesozoic landscapes. But the thermoregulatory aspect that most work is directed toward today is how dinosaurs kept warm. There is compelling evidence that dinosaurs regulated their body temperature in myriad ways, including internal chemistry. All bipedal animals today are endotherms and they all have four-chambered hearts, as dinosaurs did. , dinosaurs living near the poles (, ), and of dinosaur bones all support the idea that , but one of the more intriguing areas is that of . Like tree rings, bones have seasonal growth rings and they have been read for many dinosaur fossils. They have been used to determine dinosaurian life expectancies. could live to be about 30, giant could live to be 50, and smaller dinosaurs, as with smaller mammals, lived shorter lives. The tiny ones only lived three-to-four years and the mid-sized ones lived seven-to-fifteen years. Growth rates also provide thermoregulation evidence. Tyrannosaurs had juvenile growth spurts and largely stopped growing as adults, and sauropods had growth rates equivalent to today’s whales, which are Earth’s fastest growing animals. But there is also evidence of ectothermic dynamics. The great size of dinosaurs would have led to relatively easy ways to stay warm, as large animals have a greater mass-to-surface area ratio, like the way in which . Also, in the generally hot Mesozoic times, staying warm would have been fairly easy, particularly for huge dinosaurs.

These include turgor-driven mass flow in both.

From the Permian extinction’s devastation arose a reptilian sheep called . Fossil hunters of early Triassic sediments have been frustrated for many years, as nearly are , because it was about the Permian extinction’s only land animal survivor. There has been about why it survived when almost nothing else did. No single animal ever dominated Earth’s land masses as thoroughly as did during the early Triassic. was probably a burrower (many have likened to a pig because of that burrowing), which may have provided the shelter needed to survive the Permian holocaust. It may also have been a and could eat most surviving plants. But some think that its survival, when almost every other species died, was due to luck. Luck is a surprisingly common proposed explanation for evolutionary events and outcomes, and some creatures seemed to be in the right place at the right time while others were in the wrong place at the wrong time. The spread of was also aided by two other facts: the land masses , so could simply walk to dominance of Earth; and few predators capable of eating a survived. One (being semi-aquatic may have also helped species survive the Permian extinction), as did , but not much else did. was a , as were the dominant land animals before the Permian extinction.

The Munch’s hypothesis or mass flow or pressure flow hypothesis is proposed by E.

What is the Mass Flow Hypothesis

The , like the prior , was more than one event and had more than one cause. The is what most people think about when mass extinctions are mentioned (as it was Hollywood-spectacular and ended one fascinating line of animals and paved the way for mammals to dominate), and it led to the existence of humans, but the Permian extinction was the Big One. Before the began lifting in the 1970s and 1980s, specialists generally thought that the Permian extinction only impacted the oceans and left terrestrial ecosystems unaffected. The picture has radically changed since the 1980s, and the terrestrial extinctions are now acknowledged as similarly catastrophic. The Permian extinction is Earth’s only mass extinction of insects, and although plants are not normally vulnerable to mass extinctions, land plants also barely survived the Permian extinction. But the extinction came in phases, and each may have had different causes. There is great ongoing controversy and research regarding the issues.

Phloem: The Pressure Flow Hypothesis of Food …

Another energy-related activity probably appeared on a large scale during the reign of dinosaurs: . Although territoriality , , , , and today, it is most common among birds and mammals. Territoriality is primarily about preserving an animal’s energy base from competition, and it is usually a behavior oriented toward others of the same species, which would eat the same food resources and mate with the same potential partners. Just as what scientists call , territorial behavior may go all the way back to the . But the social behaviors apparent in dinosaurs probably also meant territorial behavior, and probably on a scale never experienced before on Earth. Even the suspected display function of implies territorial behavior. All are territorial, and human political units such as are little more than ape territoriality writ large, as peoples protect their energy and mating bases. In light of the (with its apotheosis in the peacock, although, as usual, ), and the phenomenon perhaps goes , along with the discovery of dinosaurian mass nesting sites, herd behaviors, and the like, many scientists believe that .

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Artists have been depicting Carboniferous swamps for more than a century, and the . That represents a key Carboniferous issue and perhaps why the period ended. That , and others like it, appeared in the fossil record about 300 mya, when oxygen levels were Earth’s highest ever, at somewhere between 25% and 35%. The almost universally accepted reason for that high oxygen level is that for the entire Carboniferous Period removed carbon dioxide from the atmosphere in vast amounts. Today, the estimate is that carbon dioxide fell from about 1,500 PPM at the beginning of the Carboniferous to 350 PPM by the end, which is lower than today’s value. That tandem effect of sequestering carbon and freeing oxygen not only may have led to huge arthropods and amphibians, but also intensified . The idea that high oxygen levels led to those giants was first proposed more than a century ago and dismissed, but has recently come back into favor. Flying insects have the highest metabolisms of all animals, but they do not have diaphragmatic lungs as mammals have, or air sac lungs as birds have, and although they may have some way of actively breathing by contracting their tracheas, it is not the bellows action of vertebrate lungs. The for early insect gigantism is that high oxygen, as well as a denser atmosphere (the nitrogen mass would not have fallen, so increased oxygen would have added to the atmosphere’s mass), would have enabled such leviathans to fly, and the other is that flying insects got a head start in the arms race and could grow large until predators that could catch them evolved. The late Permian had an even larger dragonfly, when oxygen levels had crashed back down. The evolution of flight is another area of great controversy, and insects accomplished it long before vertebrates did. The general idea is that flight structures evolved from those used for other purposes. For insects, wings appear to have evolved from aquatic “oars,” and gills became lungs. Reptiles did not develop flight until the Triassic, and .