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Paleozoic Life

Paleozoic Life. Life forms in the Paleozoic. The paleozoic begins with the appearance of fossils of marine animals. For the first time, ocean animals that have easily fossilized hard parts.

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Paleozoic Life

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  1. Paleozoic Life

  2. Life forms in the Paleozoic • The paleozoic begins with the appearance of fossils of marine animals. For the first time, ocean animals that have easily fossilized hard parts. • The paleozoic contains the history of animal and plant diversification in the oceans and colonization of land Crinoids

  3. Important Paleozoic Invertebrates • First we will examine the anatomical plans of Trilobites, Brachiopods, Molluscs (clams, snails and cephalopods), Echinoderms (starfish, sea urchins and especially crinoids), and Graptolites. • Later we will look at corals and sponges

  4. Trilobite shell morphology Arthropod – “jointed-leg” Related to Horseshoe crabs What other arthropods do you know of? Varied niche, predators, scavengers or filter feeders. Some swam, feeding on plankton

  5. Brachiopod morphology Sessile benthic filter feeders related to bryozoans

  6. Articulate BrachiopodsBrachiopod life positions 1 Brachiopods sort of look like a clam. However, notice that each valve is symmetrical about its middle line.

  7. Brachiopod life positions 2 Inarticulate Brachiopod Lingula Infaunal sessile benthic filter feeders intertidal

  8. Bivalve morphology Clams, Scallops Individual valve is not symmetrical about a middle line

  9. Gastropod (snail) shapes

  10. Cephalopod shell morphology

  11. Crinoid morphology Stalked echinoderm related to starfishes, sea urchins, etc

  12. Graptolites Related to ??? Often found in black shales, deep shelf waters, no other fossils Great index fossils

  13. What was the Cambrian Explosion? • The Paleozoic is marked by the abrupt appearance of animals with skeletons in the rock record • a mechanism that would trigger this event is not agreed upon, but is surely due to a combination of geologic and biologic factors • Predators prominent • shallow water, animals must be protected from UV.

  14. The Emergence of Shelly Fauna • Organisms with hard parts have many advantages • protection against UV rays, allowing animals to move into shallower water • helps prevent drying out in an intertidal environment • provides protection against predators

  15. Small shelly fauna Photos Drawings A. Mollusk B. Sponge Late Proterozoic (Ediacaran) to Early Cambria, before trilobites.

  16. Cambrian Marine Community • Many body plans are observed in Cambrian fossils, more than in any other period • trilobites – many niches, e.g. benthonic mobile sediment-deposit feeders that crawled or swam across the sea floor • brachiopods - primitive benthonic sessile suspension feeders • archaeocyathids - benthonic sessile suspension feeders and reef builders

  17. Invertebrates with hard parts Brachiopods Note how the valves have symmetry Trilobites Crinoids Sponges

  18. The Burgess Shale Biota • Consists of a rare preservation of soft-bodied organisms – Mid Cambrian • Some phyla near the basic stock from which some present-day invertebrates have evolved • Other unique and without issue • current debate centers around how many phyla arose and how many extinction events took place in the Cambrian

  19. Charles Walcott’s Burgess Shale -middle Cambrian shale in the Rockies of western Canada

  20. Anomalocaris A huge predaor Hallucigenia Pikaia A chordate!!! Sidneyia Remarkable preservation of animals’ soft tissues, plus the first predator, Anomalocaris

  21. Modern Brine Shrimp Artemiasalina Similar swimming mode to Anomalocaris? Anomalocaris A huge predaor

  22. Marella, a trilobitomorph or “Lace Crab” Anomalocaris and some known prey. Bite marks on fossils

  23. Leanchoilia--China Leanchoilia--Burgess

  24. Opabina

  25. Interpreting Hallucigenia Like the modern Peripatus, moist forests of Cameroon, Discussion: preadaptations to land if food is present

  26. Pikaia Totally unexpected find. Cartilage but no bone. Jawless ancestor to fish, and us. Maori legend of Pikea, the ancestor. Lancelets in comparative anatomy Link to lancelet info Pikaia – an early chordate! from the Burgess Shale

  27. Cambrian Trilobites

  28. Archaeocyathids (sponges?)

  29. Ordovician Marine Community Note large Orthoceras A Cephalopod Mollusk • Vast epeiric seas opened new marine habitats • bryozoans, stromatoporoids, tabulate and rugose coral reef builders • reefs with high diversity - suspension feeders • massive extinctions end Ordovician, glaciation in Gondwana & falling sea-level Cephalopods as Index Fossils

  30. Bryozoans Possibly related to Brachiopods “Moss Animals” Filter Feeders Mostly marine tropical Make hard exoskeleton, chitin or CaCO3

  31. Bryozoans In fossils, just the exoskeleton is preserved

  32. Halysites Tabulate Coral O-S

  33. Stromatoporoid - Hydrozoan coral or Sponge? C - K -

  34. Graptolite

  35. Silurian and Devonian Marine Communities • Rapid diversification and recovery followed the Ordovician mass extinction • reef building by tabulate and rugose corals • NEW PREDATOR : Eurypterids were abundant • Ammonoids evolved quickly and are important as index fossils • mass extinction at the end of the Devonian collapsed the massive reefs Marine “Scorpions” Track ways in coastal sands Probably laid eggs as horseshoe crabs do along the foreshore Pterygotus

  36. Rugose Corals – individual animals Field Trip, Stroudsburg, PA

  37. Devonian Tabulate Corals Colonial

  38. Brachiopod

  39. Carboniferous and Permian Marine Communities • Renewed diversity and recovery with adaptations mark the Late Paleozoic marine communities • bryozoans and crinoids reach their greatest diversity • patch reefs replace the massive reefs of the Devonian –TEMPS? • fusulinid formanifera are important index fossils

  40. Types of Staked Echinoderms 1 Cystoids

  41. Types of Staked Echinoderms 2 Blastoids

  42. Fragments on Field Trip Stroudsburg PA Types of Staked Echinoderms 3 - Crinoids

  43. Vertebrate Evolution • Chordates have, during at least part of their life, a notochord, dorsal hollow nerve chord, and gill slits • Vertebrates have backbones and are a sub-phylum of chordates • ancestors were soft-bodied and left few fossils • a close relationship exists between echinoderms and chordates and they may have shared a common ancestor

  44. Fish • Fish range from the Late Cambrian to the present and consist of five classes • Ostracoderms • Placoderms • Acanthodians • Cartilaginous fish – sharks and rays • Bony fish

  45. Classes of fish through time

  46. Ostracoderms- Jawless fish Field Trip Bony plates in Shf Silurian High Falls at Delaware Water Gap

  47. Evolution of jaws

  48. Placoderms – first fish w jaws Dunkleosteous (Dinichthys) a Devonian arthrodire

  49. Placoderm - Bothryolepis • Today we will examine another Placoderm • Named Bothryolepis • It’s armor is similar to that of modern South American catfishes that live in shallow, fast moving, jungle streams in South America

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