(BENS) Fossil and DNA Evidence Lesson
Fossil and DNA Evidence Lesson
Fossils also provide evidence of evolution. A fossil is the remains or traces of an organism that lived in the past. Fossils usually form when an organism dies and after millions of years the bones or a shell of the organism is buried in layers of sediments that becomes sedimentary rock.
Scientists can use the fossil remains of an organism to determine its feeding behavior, reproductive methods, parental care, and also what type of environment it may have lived in the past.
The four major types of fossils are:
- Mold fossils (a fossilized impression made in rock)
- Cast fossils (formed when a mold is filled in)
- Trace fossils (fossilized nests, imprints of plants, burrows, footprints, etc.)
- Preserved fossils (fossils of the actual animal or animal part preserved in ice, tar, amber, etc.)
- Petrified fossils (fossilized remains in rock)
Fossils show how a species of organisms have changed over time. For example, the earliest form of a horse had four toes on each front foot. Over time, those toes became a single hoof. The fossil remains of the earliest known horse suggest that it took about 50 -55 million years for the animal to evolve from the size of a small dog to the size of a modern horse.
The diversity of life is incredible; yet what we see today is only a tiny view of all the different kinds of life that existed in the past. Fossils are windows into time that let us see what living things once were like. From the discoveries of dinosaur fossils we can learn how continents have moved, how climates and landscapes have changed and how life has evolved. Watch the following video to learn more about how we use fossils to gain a better understanding of our world. The video is approximately 25 minutes long. Pause the video when necessary to make notes.
On May 28, 2008 the remains of the world's oldest known mother were unearthed in the Australian outback.
Humans have walked the Earth for 190,000 years. That is a mere blip in Earth's 4.5-billion-year history. A great deal has happened in that time. Earth formed and oxygen levels rose in the foundational years of the Precambrian. The productive Paleozoic era gave rise to hard-shelled organisms, vertebrates, amphibians, and reptiles. Dinosaurs ruled the Earth in the mighty Mesozoic. And 64 million years after dinosaurs went extinct, modern humans emerged in the Cenozoic era. The planet has seen an incredible series of changes.
Bonehead Detectives of the Paleoworld: Mystery of the Neanderthal
Join in the debate on the origins of modern day Homo sapiens. Watch the following video, Bonehead Detectives of the Paleoworld: Mystery of the Neanderthal. Did they conquer the earlier Neanderthals, or did an earlier form of Homo sapiens merge its gene pool with Neanderthal to create modern man? Video narrators Sam and Allie study Neanderthal tools and fossils, as well as speak with experts on Neanderthal behavior. The video is approximately 23 minutes long. Pause the video when necessary to make notes.
Can you answer the following self-assessment questions about evolution? Click on the question marks to see the answers:
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