The Rise Of Flowering Plants - Cretaceous Period - Prehistoric Life

The Rise Of Flowering Plants
Until the Early Cretaceous Epoch, the world's flora was dominated by ferns and gymnosperms—seed plants whose seed embryos are not protected by a fruit, cone, or other body. Gymnosperms first appeared in the late Paleozoic Era and became dominant during the first half of the Mesozoic Era. They are still represented today by more than 600 known species of conifers (evergreen trees), cy-cads, gnetophytes, and Ginkgo, none of which have flowers or fruits. Gymnosperms are typically tough and hearty. Their woody pulp, thick bark, branches, and needles or frondlike leaves are difficult to chew. Herbivorous dinosaurs of the Jurassic Period—including the sauropods, stegosaurs, and ankylosaurs—developed jaws, teeth, and digestive systems capable of extracting nutrition from the likes of evergreens, cycads, and other tough gymnosperms. The animals' basic digestive strategy was to minimize chewing of the food in the mouth and to use a fermentation process in the stomach to slowly extract nourishment from the nutritionally stingy gymnosperms.
Gymnosperms were successful at surviving in a Jurassic world with a moderately warm and arid climate. They relied only on wind to carry pollen to their seeds. Pollinated gymnosperm seeds grew slowly, and when fully grown they often took the form of tall trees in species such as ginkgos and conifers. Slow growth and height discouraged consumption by herbivores. Sauropod dinosaurs adapted by growing taller to reach the ever-more-lofty canopies of gymno-sperms and also developed consumption habits that allowed them to eat fairly constantly in order to derive enough sustenance from the nutritionally stingy conifers and cycads.
(continues on page 28)
THINK ABOUT IT
Dinosaurs of the Poles
The polar regions of today's world are the coldest and harshest on the planet. Most kinds of organisms would not survive for long if left to fend for themselves above the Arctic Circle or in Antarctica. The polar regions of the Earth were not always so uninhabitable, however, and there is growing evidence that a wide variety of dinosaurs lived within the polar circles of the Mesozoic.
Even though the middle latitudes of the Earth were uniformly warm during the Mesozoic Era, temperatures at the poles would have been somewhat cooler, even without the presence of ice caps. Studies of fossil plants and associated oxygen isotope studies of polar sediments have been carried out to determine the average annual temperatures of the Mesozoic polar regions. Results suggest that the North Pole had a mean average temperature between 36° and 46°F (2° and 8 °C) and the South Pole about 50 °F (10 °C)—not tropical temperatures by any means, but not below freezing, either. Another factor affecting life on the extreme ends of the planet would have been prolonged periods of darkness and cooler temperatures still during winter.
The idea that dinosaurs could have lived at the relatively cool poles of the Earth was virtually unthinkable 50 years ago because of the widespread belief that their metabolism was more like that of cold-blooded modern reptiles than that of birds or mammals. The work of paleontologists to collect fossils in these regions during the past 20 years has led to a change of thinking. Not only did dinosaurs colonize the poles by at least 190 million years ago, but fragmentary remains have now been identified there for nearly all major branches of the dinosaur evolutionary tree, with the notable and interesting exception of sauropods.
"Polar" dinosaurs—as defined by paleontologists Thomas Rich (Museum of Victoria, Australia); Roland Gangloff (University of Alaska); and William Hammer (Augustana College, Illinois)—are defined as those dinosaurs "that lived within the polar circles of their time, not necessarily within the current polar circles." This means that their fossils are sometimes found on landmasses that have since drifted to the fringes of the ancient polar circles, such as Australia and New Zealand in the south and Alaska, Russia, and the Canadian Yukon in the north.
One of the most productive fossil sites for polar dinosaurs is found on the banks of the Colville River in northeast Alaska. Evidence of polar dinosaurs is usually scant. The most complete dinosaur from any polar locality was found at the Matanuska Formation of south-central Alaska in 1995 and consisted of about a quarter of the animal. Bones from the foot, limbs, and tail were enough to convince paleontologist Anne Pasch of the University of Alaska that what had been found was a specimen of a hadrosaur—a duck-billed dinosaur. Dating of the fossil sediments was made easier by the presence of sea creatures such as ammonites, the age of which can be fixed at about 90 million years ago. That's about 10 million years older than other hadrosaurs from North America and suggests that the Alaskan duckbill might be linked to early hadrosaurs from Asia. Finding the bones of terrestrial animals in marine deposits is not so unusual, although the specimens are usually spotty and incomplete. Pasch speculated that the hadrosaur died on the shore of an ancient ocean and "floated out to sea, probably as a bloated carcass. It eventually sank to the bottom and was buried in fine black mud along with shells and other sea creatures" found with its bones.
Most main groups of dinosaurs are represented by fossil evidence from regions that would have been polar during the Mesozoic. In the Northern Hemisphere, compelling evidence of hadrosaurs, horned dinosaurs, large and small theropods, sauropods, and plated and armored dinosaurs is found in the northern reaches of Alaska, Canada, and Siberia. In the Southern Hemisphere, polar dinosaurs are represented by specimens of armored dinosaurs, smallornithopods, hadrosaurs, prosauropods, sauro-pods, large and small theropods, and possible horned dinosaurs. These remains are not alone and are often found with fossils of other creatures
Ccontinues)
(continued)
from the polar neighborhood such as crocodilians, amphibians, pterosaurs, birds, and small mammals.
The presence of polar dinosaurs cannot be denied but raises questions about their lifestyle, metabolism, and thermoregulation. Chief among these questions is whether the presence of dinosaurs in cooler regions of the world is evidence of a more active, energetic thermoregulatory metabolism, or whether there was more to the story. Australian paleontologists Thomas Rich and Patricia Vickers Rich, who have done much to advance knowledge of polar dinosaurs of the Southern Hemisphere, speculate that some small dinosaurs may have actually burrowed into the ground to protect themselves against the chill of the long winter nights. Another plausible idea is that some dinosaur groups migrated to the south toward the poles during seasonally warmer periods and returned toward the Equator when the winter chill set in. That would have been possible given the configuration of connected landmasses during much of the Mesozoic. Another clue to dinosaur survival in colder climates might also be related to the possible use of feathers as a form of body insulation—at least for small theropods for which such body coverings have been found.
(continued from page 25)
The dominance of gymnosperms diminished during the Cretaceous Period with the rise of flowering plants—the angiosperms. Angiosperms were characterized by a new reproductive life cycle that quickened their ability to grow, breed, and disperse. Angio-sperms utilize flowers to attract pollinating animals, such as insects, and also encase their seeds in fruits that, when separated from the plant, can aid in dispersal of seeds. The innovations of flowers to aid in pollination and fruits to protect the embryo contributed to the rapid success and spread of flowering plants. The oldest known
A fossil of a gymnosperm
angiosperm dates from the Early Cretaceous Period, about 125 million years ago. Found in the same Chinese fossil region that contains exciting fossils of early marsupial and placental mammals, feathered dinosaurs, and birds, this primitive early example of a flowering
A fossil of an angiosperm
plant had paired stamens (the pollen-producing parts of a plant) and multiseeded fruits, although it may have lacked flowers.
Angiosperms quickly became a favorite food of dinosaurs. Flowering plants reproduced much more quickly than gymnosperms; angiosperms constantly replenished a landscape that could become heavily browsed by hungry dinosaurs. The ability of angiosperms to grow rapidly and disperse widely allowed them to diversify into hundreds of species by the end of the Cretaceous Period. The
An early magnolia from the Cretaceous Period
importance of the angiosperms to the evolution of dinosaurs cannot be understated. The Cretaceous Period is known for an explosion of new lines of ornithischians—duck-billed, armored, and horned dinosaurs in particular—that developed specialized adaptations for chewing and consuming the wider assortment of vegetation available to them, including the recently evolved flowering plants and gymnosperms. Those special anatomical features will be explored in Section Three of Last of the Dinosaurs, in the discussion of ornithischians of the Cretaceous Period.
Readers' Questions
Trilobites: These were arthropods that thrived in the oceans, evolving various forms and sizes. They were highly diverse and abundant during the Paleozoic Era.
Brachiopods: These were marine invertebrates that had a hinged shell, similar to a clam. They were also quite diverse during this era.
Ammonites: These were cephalopods that had a coiled shell. They were present in the oceans and underwent significant diversification during the Paleozoic Era.
Plants: Land plants, such as ferns and early seed-bearing plants, originated and diversified during the Paleozoic Era. Some plants, like the giant tree-like Lepidodendron, were particularly prominent.
Fish: Jawed fish, such as the armored fishes (placoderms) and cartilaginous fishes, were prevalent in the Paleozoic Era. These early fish laid the foundation for the evolution of more advanced fish groups.
Reptiles: The earliest reptiles, including the reptile-like amphibians called the temnospondyls, began to emerge during the Paleozoic Era.
Insects: Insects evolved and diversified during the Paleozoic Era. They underwent significant adaptations, including the development of wings, leading to the emergence of various insect groups.
Corals: Various types of coral groups, including rugose and tabulate corals, thrived in the oceans during the Paleozoic Era. These reefs played a vital ecological role.
These are just a few examples of the organisms that arose during the Paleozoic Era. The era was marked by a significant diversification and evolution of life, with numerous new species emerging in various habitats.
Angiosperms, or flowering plants, are believed to have evolved during the Early Cretaceous period, around 140 to 130 million years ago. This evolutionary development was a significant event in the history of plants, as angiosperms quickly became the dominant plant group on Earth.
Fruits evolved approximately 80-100 million years ago, during the Late Cretaceous period. This coincides with the diversification of flowering plants (angiosperms) and the development of various mechanisms for seed dispersal, including the formation of fruits.
leanna
Which of the following is not a reason for the success of the dinosaurs?
Flowers have been on Earth for approximately 140 million years. The oldest known flower fossils date back to the Early Cretaceous period, which began around 140 million years ago. However, it is believed that flowers may have evolved even earlier than that, possibly during the late Jurassic period.
It is not possible to definitively answer this question because the fossil record from the Cretaceous period (145 million to 66 million years ago) is not extensive enough to provide enough evidence to know exactly which flowers existed during that time. However, it is possible that some of the flowers that existed during this time period included water lilies, magnolias, buttercups, and possibly even roses.
semira
Which time period saw the rise of flowering plants, mammals, large reptiles, and marsupials?
Breakup of Pangea: The supercontinent Pangea began to break up during the Jurassic Period, creating the modern continents of Europe, Africa, North America, South America, Australia, and Antarctica.
Appearance of Dinosaurs: Dinosaurs first appeared during the Triassic period but flourished during the Jurassic. This period saw the evolution of many dinosaur species, including Diplodocus and Brachiosaurus.
Rise of Modern Birds: The first true birds evolved during the Jurassic period, giving rise to most modern forms of birds.
Expansion of Flora: The Jurassic Period saw the proliferation of lush vegetation, which provided food for the dinosaurs and other animals living at the time.
Development of Marine Reptiles: The Jurassic Period also saw the evolution of large marine reptiles such as ichthyosaurs and plesiosaurs.
Volcanic Activity: During the Jurassic Period, there was an increase in volcanic activity, which contributed to global climate change.
Global climatic change gave gymnosperms an advantage over ferns by providing them with a better chance of survival. Gymnosperms are able to withstand much more extreme conditions than ferns, including hotter climates and drier soils. They also have evolved more efficient strategies for water conservation, which have allowed them to thrive in areas that have recently become drier during periods of global climatic change. This gives them an advantage over ferns, which are much less well-adapted to dry environments.
claudia
What advantage did gymnosperms have over more primitive types of plants?
Gymnosperms had a reproductive advantage over more primitive plants because their reproductive structures were not dependent upon water for fertilization. Also, the presence of an exposed seed allowed for the easy dispersal of their progeny by wind, animals, and other means. The tougher, woody nature of their stems and leaves gave them a competitive advantage over more delicate primitive plants.
Fruits have played a major role in the success of angiosperms. Fruits provide an effective means of dispersal for many plants, enabling them to spread their seeds far and wide. Fruits also attract animals, which help spread seeds. Fruits provide a nutritious food source for animals, and in exchange, animals carry the seeds of the fruits to other places, pollinating and dispersing the plants in the process. This form of seed dispersal is known as endozoochory. Additionally, some fruits provide the energy for seed germination, helping to promote the successful establishment of new plants. Finally, fruits can provide insulation for the developing seeds and embryos of many plants, protecting them from the elements and helping them to survive.
Angiosperms are more successful than gymnosperms because they have various adaptations that have enabled them to thrive in many different environments and to become the most widespread and diverse group of plants on Earth. Angiosperms are able to reproduce more efficiently than gymnosperms, producing seeds that are enclosed by fruit. This has allowed angiosperms to disperse their seeds more widely than gymnosperms, increasing their chances of surviving and thriving in new environments. Additionally, angiosperms can cross-pollinate and self-pollinate, which allows them to produce an abundance of fertile seeds. Finally, angiosperms have adaptations that enable them to survive in a greater range of climates and habitats than gymnosperms. These adaptations include leaves that can adapt to different light intensities, roots that can absorb nutrients from different depths in the soil, and flowers that can attract different pollinators.
The dominant organisms living in the Jurassic Period included primitive amphibians, reptiles such as dinosaurs, giant insects, and early birds. Other organisms included small mammals, fish, and plants, including ferns, cycads, conifers, and ginkgos.
The exact height of trees in prehistoric times is impossible to determine, as there are no surviving tree ring records from that period. However, the fossilized leaves, cones, and seeds from some of the earliest trees suggest that they typically reached heights of 30-40 feet.
Ferns do not grow as tall as gymnosperms and angiosperms because they lack the vascular system that is responsible for transporting water, minerals, and other resources up the stem. Without a strong vascular system, ferns rely on moisture in the environment to survive, which limits their growth.
Elias
What type of organisms are important in the evolution of flowering plants?
Pollinators such as bees, butterflies, and hummingbirds play an important role in the evolution of flowering plants. These organisms feed on the nectar and pollen of flowers and, in doing so, help to spread and cross-pollinate the plants, thus allowing them to evolve and develop. In addition, many plants rely on mutualistic relationships with insects and other animals for pollination, dispersal of seeds, and dispersal of nutrients. Without these helpful organisms, the evolution of flowering plants may have been drastically different.
A notable plant of the Cretaceous period was cycads, a type of ancient gymnosperm. They were typically tropical plants which grew in humid environments and had prominent trunks and fern-like leaves. Other plants that were common during this period included conifers, ferns, ginkgoes, and a variety of flowering plants.
Drawing flowers during the Cretaceous period would be quite a challenge! It is difficult to know exactly what flowers may have looked like during that time period since the fossil record is not very clear. However, you could use some creative license to draw flowers that would fit in with the flora of the time.
Some suggestions for creating a "Cretaceous Period" flower drawing would be to use colors from plants that grew in the Cretaceous, such as greens, yellows, and oranges. You could also use shapes that are more angular or geometric, as these shapes were more common for plants of the time. Additionally, you could research images of fossilized flowers from the Cretaceous period to get a better idea of the types of shapes and color palettes that were present then.
It is difficult to answer this question definitively due to a lack of detailed records from this period. However, some flowering plants which are thought to have existed during the Dark Ages include: Primrose, Rose, Mistletoe, Sundew, Buttercup, Daisy, Anemone, Bellflower, Columbine, Primula, and Violets.
Some of the plants that thrived during the Cretaceous period include conifers, cycads, ginkgoes, and various types of flowering plants. Other plants that flourished during this era include ferns, grasses, horsetails, and club mosses.
The Cretaceous period saw the development of conifer and angiosperm trees, as well as ferns, cycads, ginkgos, and early flowering plants. Grasses and herbaceous plants were also abundant. Marine algae and other aquatic plant life were also diverse.
The late Paleozoic Era (approximately 300-250 million years ago) was a time of great biological diversity, and amphibians were no exception. During this period, the Earth experienced global warming, continental drift, and high levels of oxygen in the atmosphere, all of which provided a conducive environment for the diversification of amphibians and other species. The increased availability of niches and resources, as well as the lack of competition from other vertebrate groups, likely allowed amphibians to diversify quickly.
The Cretaceous period lasted from 145 million to 66 million years ago. During this period, the Earth experienced major climate changes and the mass extinction of the dinosaurs. Other important events that occurred during this period include the diversification of flowering plants, the evolution of birds, the emergence of mammals, and the formation of Pangaea. In addition, the seas were teeming with life and coral reefs were widespread.
The Cretaceous period was home to a wide variety of animals, including the dinosaurs that were the dominant species of the time. Other animals that lived during this period include woolly mammoths, saber-toothed cats, ammonites, crocodiles, turtles, pterosaurs, and marine reptiles such as mosasaurs and plesiosaurs. Many modern animal families also developed during this time, including snakes, lizards, birds, and mammals.
Some dinosaurs may have eaten fruit, but mainly the herbivorous dinosaurs. Some of the fruit available to them in the Mesozoic Era would have included conifer cones, cycads, and ginkgo. The fossilized remains of these ancient fruits have been found in dinosaur droppings.
It is impossible to provide an exact number, as the fossil record of flowering plants is incomplete. However, it is estimated that there were hundreds of species of flowering plants during the Cretaceous period.
During the Cretaceous period, plants stabilized oxygen levels by producing more oxygen during photosynthesis and absorbing more carbon dioxide during respiration. Additionally, faster rates of weathering of rocks due to increased temperatures and increased rainfall contributed to greater amounts of oxygen being released into the atmosphere. This oxygenation of the atmosphere allowed for the proliferation of numerous species that require oxygen for respiration.
The plants that grew in the Cretaceous period (145.5 to 65.5 million years ago) include conifers, ginkgo trees, cycads, pteridophytes, flowering plants, and ferns. Also present were various species of mosses, liverworts, and horsetails.
Fossil evidence suggests that the fruits available during the Jurassic period were largely primitive varieties, such as primitive apples, pears, plums, peaches, and apricots. Other primitive fruits that may have been available include cherries, dates, figs, and olives.