plant radiation: an ecological hypothesis
What is the Devonian Plant Hypothesis?
As scientists know with mammals, although , it comes with a great energetic cost. As with plants, an animal can spend its on consumption (metabolism) or investment (growth). An intriguing hypothesis is that growing large was part of an energy strategy, as the benefits of size (reduced risk of predation, ease of conserving body heat and consequently less need for a high metabolism, ability to access new food sources, such as foliage high above the ground) outweighed their costs (energy devoted to growth instead of metabolism, the need to constantly feed). Their size and the warm climate meant that large dinosaurs did not need as intense internal energy generation as mammals do, for instance, and dinosaurs may have been , with internal energy regulation greater than , but not as great as (mammals and birds).
The Devonian: The Plant World and the Animal World
Conifer forests, which , first . Devonian forests were 10 meters tall, Carboniferous rainforests were 30 meters tall, and Mesozoic conifers reached 60 meters tall and even sequoias appeared. Conifers were one of the early seed plants and used pollen to fertilize their seeds; that method that did not need the water that spores did. As conifers appeared during an ice age, they are well-adapted to cold climates, which is why conifer forests are so prevalent today. As , conifers were later displaced by , which engaged in an unprecedented symbiosis with animals, and conifers were pushed to Earth’s cold margins. declined after the Carboniferous, but still exist today.