1 / 41

Paleontology Studying The Fossil Record

Paleontology Studying The Fossil Record. Phylogeny. The evolutionary history of a species or a group of species over geologic time. The Fossil Record and Geologic Time. Phylogeny is backed by the fossil record.

quentin-good
Download Presentation

Paleontology Studying The Fossil Record

An Image/Link below is provided (as is) to download presentation Download Policy: Content on the Website is provided to you AS IS for your information and personal use and may not be sold / licensed / shared on other websites without getting consent from its author. Content is provided to you AS IS for your information and personal use only. Download presentation by click this link. While downloading, if for some reason you are not able to download a presentation, the publisher may have deleted the file from their server. During download, if you can't get a presentation, the file might be deleted by the publisher.

E N D

Presentation Transcript

  1. Paleontology Studying The Fossil Record

  2. Phylogeny The evolutionary history of a species or a group of species over geologic time

  3. The Fossil Record and Geologic Time Phylogeny is backed by the fossil record. The fossil record refers to the order in which fossils appear within layers of rock that mark the passing of geologic time. Which layer do you think is the oldest?

  4. The Fossil Record and Geologic Time When rocks are in layers it is usually a sign that the rocks are sedimentary rocks. Sedimentary rocks are the richest source of fossils.

  5. The Fossil Record and Geologic Time Specific conditions are needed for fossilization. Only a tiny percentage of living things became fossils.

  6. Types of Fossils - Permineralization Organic substances in dead organisms typically decay rapidly.  Parts that are rich in minerals (e.g., teeth, bones) may become fossils by permineralization. Permineralization occurs after burial, as the empty spaces within an organism’s hard parts (spaces filled with liquid or gas during life) become filled with mineral-rich groundwater and the minerals precipitate from the groundwater, thus occupying the empty spaces.

  7. Types of Fossils – Casts and Molds In some cases the original remains of the organism have been completely dissolved or otherwise destroyed. When all that is left is an organism-shaped hole in the rock, it is called an external mold. If this hole is later filled with other minerals, it is a cast. An internal mold is formed when sediments or minerals fill the internal cavity of an organism, such as the inside of a bivalve or snail. External Mold Cast

  8. Types of Fossils – Trace Fossils Trace fossils are the remains of trackways, burrows, eggs and eggshells, nests, droppings and other types of impressions. Fossilized droppings, called coprolites, can give insight into the feeding behavior of animals and can therefore be of great importance. Coprolites Tracks

  9. Types of Fossils – Fossil Resin Fossil resin (colloquially called amber) is a natural polymer found in many types of strata throughout the world, even the Arctic. The oldest fossil resin dates to the Triassic, though most dates to the Tertiary.

  10. What kind of fossil is each of these?

  11. Paleontologists use many methods to date fossils. Relative dating Fossils near the surface are relatively recent, while those that are deeper are relatively older. Geologists have established a geologic time scale that reflects a consistent sequence of historical periods. Those periods are grouped into four eras:  Precambrian, Paleozoic, Mesozoic, and Cenozoic.

  12. Absolute dating – age is given in years, instead of relative terms (before/after, early/late). Radiometric dating is the measurement of radioactive isotopes found in fossils and rocks, to determine age. The half-life of an isotope is the number of years it takes for 50% of the original sample to decay.

  13. The fossil record is substantial, but does not provide a complete evolutionary history. The fossil record usually tells us about abundant, widespread organisms with hard shells or skeletons.

  14. Phylogeny has a biogeographic basis in continental drift. Moving continents isolate populations, allowing for evolution to occur. 250 million years ago all continents were connected as Pangaea. Pangaea “broke” apart about 180 million years ago.

  15. Mass Extinctions Mass extinctions often changed the complexion of entire ecosystems and food webs resulting in species, genera, families and even higher taxa dying out.

  16. Geological Timeline

  17. Precambrian 4,500-550 mya The Precambrian is an informal name for the supereon comprising the eons of the geologic timescale that came before the current Phanerozoic eon. Stromatolites First single-celled organisms, simple plants, and invertebrate animals: algae, bacteria, jellyfish, flagellates, amoebas, worms, sponges 4,500-550 mya (millions of years ago)

  18. Cambrian Period 550-505 mya Stromatolites First trilobites, forams, brachiopods, nautiloids, clams, snails, crustaceans, crinoids, gastropods, corals, protozoans The Age of Trilobites

  19. Cambrian Period 550-505 mya Complex organisms became gradually more common in the millions of years immediately preceding the Cambrian, but it wasn't until this period that mineralized - hence readily fossilized - organisms became common. Most of the continents resembled deserts spanning from horizon to horizon. Stromatolites The diversification of lifeforms was relatively rapid during this period, and is termed the Cambrian explosion.

  20. Ordovician Period505-438 mya First starfish, sea urchins, blastoids, eurypterids, bryozoa, scaphopods, jawless fish, echinoids. The Age of Cephalopods

  21. Silurian Period438-408 mya An eurypterid, a prehistoric sea scorpion First land plants, ferns, sharks, boney fish, water scorpions. The Age of Coral

  22. Devonian Period408-360 mya Early tetrapods Acanthostega (foreground) and Ichthyostega. First insects, tetrapods, ammonites, placoderms. The Age of Fishes

  23. Carboniferous PeriodMississippian Epoch360-325 mya Crinoid meadow in a shallow sea The Age of Crinoids First reptiles, spiders, amphibians. Why is it called the Carboniferous Period? Hint: There was no fungi to decompose the dead trees.

  24. Carboniferous PeriodPennsylvanian Epoch325-286 mya First conifers, synapsids The Age of Plants and Giant Insects Dragonfly: 75 centimeter wingspan

  25. Permian Period286-248 mya Heyday of synapsids, including pelycosaurs The Age of Amphibians Early

  26. Permian Extinction248-251 mya The Permian–Triassic (P–Tr) extinction event, informally known as the Great Dying, was an extinction event that occurred about 250 million years ago, forming the boundary between the Permian and Triassic geologic periods.

  27. Permian Extinction248-251 mya It was the Earth's most severe extinction event, with up to 96 percent of all marine species and 70 percent of terrestrial vertebrate species becoming extinct; it is the only known mass extinction of insects. 57% of all families and 83% of all genera were killed off. Because so much biodiversity was lost, the recovery of life on earth took significantly longer (10 to 50 million years) than after other extinction events. This event has been described as the "mother of all mass extinctions".

  28. Permian Extinction248-251 mya There are several proposed mechanisms for the extinctions; An earlier peak was likely due to gradualistic environmental change such as sea-level change, anoxia, increasing aridity, and a shift in ocean circulation driven by climate change. The later peak was probably due to a catastrophic event(s) such as impact events, increased volcanism, or sudden release of methane hydrates from the sea floor

  29. Triassic Period248-213 mya First turtles, cycads, lizards, dinosaurs, mammals The Age of Dinosaurs (1)

  30. Jurassic Period213-145 mya First squids, frogs, birds, salamanders The Age of Dinosaurs (2)

  31. Cretaceous Period145-65 mya The Age of Dinosaurs (3) First flowering plants, snakes, modern fish, rise and fall of toothed birds, heyday of dinosaurs

  32. The K-T Extinction65.5 mya The Cretaceous–Tertiary extinction event was a large-scale mass extinction of animal and plant species in a geologically short period of time. Widely known as the K–T extinction event, it is associated with a geological signature known as the K–T boundary, usually a thin band of sedimentation found in various parts of the world.

  33. The K-T Extinction65.5 mya Scientists theorize that the K–T extinctions were caused by one or more catastrophic events, such as massive asteroid impacts (like the Chicxulub impact), or increased volcanic activity. 85% of all species died in the K-T extinction.

  34. The K-T Extinction65.5 mya

  35. The K-T Extinction65.5 mya Several impact craters and massive volcanic activity, such as that in the Deccan traps, have been dated to the approximate time of the extinction event. These geological events may have reduced sunlight and hindered photosynthesis, leading to a massive disruption in Earth's ecology. K-T boundary layer Iridium is extremely rare in normal rock but common in asteroids.

  36. Tertiary Period65-1.8 mya Diversification of mammals, first marine and large terrestrial animals, horses, whales, monkeys, first grasses, apes, anthropoids, first hominids. The Age of Mammals

  37. Quaternary Period1.8 mya to present Mammoths, mastodons, Neanderthals, first modern human beings (Homo sapiens) The Age of Mammals

More Related