Ordovician development of Life and Land. Jarðsaga 1 -Saga Lífs og Lands Ólafur Ingólfsson

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1 The Early Paleozoic World Late Cambrian and Early Ordovician development of Life and Land Jarðsaga 1 -Saga Lífs og Lands Ólafur Ingólfsson

2 Role of oxygen in Cambrian evolution Oxygen priorities: Low oxygen levels: respiration & tissue synthesis High oxygen levels: oxygen can be used for lower priority things - skeletons, shells, etc. Oxygen reached critical threshold in Cambrian, eliminating the need for priorities. Evidence: modern low O2 environments have only small, soft-bodied forms.

3 The Late Cambrian n Globe

4 The Late Cambrian Climate

5 Fossil Assemblages of the Proterozoic - Cambrian boundary

6 Windows into the Past: Chengjiang Lagerstatten

7 Chengjiang Lagerstatten Sinoburius lunaris Xandarella spectaculum Squamacula clypeta

Late Cambrian development of life Trilobites, brachiopods, and other typical

downwards to deeper water Trace fossils made by animals show that the animals of

8 Late Cambrian development of life Trilobites, brachiopods, and other typical Cambrian groups continued to flourish. Molluscs diversified. During this time grazing increased. Mat scratchers and mat miners migrated upwards towards littoral zone and downwards to deeper water Trace fossils made by animals show that the animals of the Cambrian were developing new ecological niches and strategies - such as active hunting, burrowing deeply into sediment, and making complex branching burrows.

9 Almost every metazoan phylum arrived on the Cambrian scene... Almost every metazoan phylum with hard parts, and many that lack hard parts, made their first appearance in the Cambrian. The only modern phylum to appear after the Cambrian was the phylum Bryozoa (mosadýr), which is not known before the early Ordovician.

FUNGI club fungi sac fungi PLANTS ANIMALS flowering plants arthropods chordates conifers annelids cycads mollusks echinoderms ginkgo ferns ribbon gnetophytes worms horsetails roundworms flatworms

10 FUNGI club fungi sac fungi PLANTS ANIMALS flowering plants arthropods chordates conifers annelids cycads mollusks echinoderms ginkgo ferns ribbon gnetophytes worms horsetails roundworms flatworms lycophytes mosses, rotifers liverworts cnidarians whisk ferns, hornworts sponges comb jellies zygomycetes chytrids red algae green algae brown algae diatoms dinoflagellates chrysophytes ciliated protozoans euglenoids Trichoplax flagellated protozoans sporozoans PROTISTANS water molds slime molds amoeboid protozoans eubacteria MONERANS archaebacteria chemical origin of life

11 The Early Cambrian Radiation With abundant oxygen, phyla underwent adaptive radiation, but many early phyla did not stand up to competition

12 Metazoan Diversification: Molluscs

13 Metazoan diversification: The Echinoderms (Skrápdýr)

14 The Conodonts The conodonts first appear duringthelatecambrian. Thesewereprobablyfast swimming micro-predators, soft-bodied animals, now considered to be among the first vertebrates, with flattened elongate eel-like bodies. They are known almost entirely from their hard (calcium phosphate) tooth-like elements, but a few instances of soft tissue preservation revealed their physical form. The wide variety in conodont teeth suggestthatevenat thisearly stage in the evolution of life, they were part of a com-plex ecosystem of predator and prey

15 Cephalochordates: Primitive, Fish-Like Forms (appear by at least Middle Cambrian) Amphioxus conodonts conodont animal

16 Cartilaginous fishes Bony Fishes Primitive Fishes

(brynfiskar), which appeared in thelatecambrianperiod, about 510 million years ago,

17 The fishes start to evolve... The first fishes, and among the first vertebrates, were the ostracoderms (brynfiskar), which appeared in thelatecambrianperiod, about 510 million years ago, and became extinct at the end of the Devonian, about 350 million years ago. The internal skeletons of these jawless creatures are rarely preserved.

18 Poor swimmers Ostracoderms had bony external shields that covered the head and most of the trunk. From 9-30 cm long, ostracoderms had rather thick, flattened bodies with only a pair of side flaps to help in steering. They probably swam clumsily just above the sea floor. The mouth served to obtain oxygen and to retain bits of food.

19 Early Paleozoic Ostracoderms (Jawless fishes)

20 Recurring extinctions during the Cambrian Period

21 The Cambrian extinction first of a number of such events through Earth s history

A major extinction by the end of the Cambrian. Why?

killed off a number of unique taxa, including: the last

manytrilobites basal arachnomorphs (fjölfætlur) several

22 A major extinction by the end of the Cambrian. Why? The very end of the Cambrian saw a mass extinction that killed off a number of unique taxa, including: the last archaeocyathids the anomalocarids many lobopods (worms) manytrilobites basal arachnomorphs (fjölfætlur) several orders of early nautiloids (kuggar) a number of primitive echinoderms

23 What does it take to survive...? During the Cambrium and most of the Ordovician, sea levels were high. On the continental shelves, marine organisms engage in evolutionary experiments. The number of families of known marine invertebrates increases from about 200 at the end of the Cambrian to around 500 in the early Ordovician. Pikaina

24 Evolutionary experiments: Strange animals... Haplophrentis carinatus Wiwaxia corrugata Marrella splendens Hallucigenia sparsa Opabinia regalis Amiskwia sagittiformis

Did groups go extinct because they failed to diversify rapidly? Few questions on extinctions ns and survival Were victims of early extinctions biologically inferior to the groups that survived?

25 Did groups go extinct because they failed to diversify rapidly? Few questions on extinctions ns and survival Were victims of early extinctions biologically inferior to the groups that survived? Were they less effective in competing with other taxa or in avoiding predators? Can extinctions of whole groups be blamed on predators? Were they maybe simply the unlucky victims of catastrophic extinctions that struck species regardless of their ecological abilities?

26 Stephen Jay Gould Radical Thinker Could some Burgess Shale organisms belong to extinct phyla? Is it possible that a phylum could be represented by few or single species? If so, suggests that the Cambrian Explosion produced more phyla than are present today extinction Conventional view: Gradual increase in number of phyla through time Gould s View: Sudden appearance of phyla, removal of many by mass extinction

27 Cause(s) of Cambrian extintion(s) ion(s) not known... During the Late Cambrian alone, there were three distinct bio-stratigraphic intervals in trilobite distribution, each marked by a massextinction. The cause(s) of the late Cambrian extinction(s) are not known, but it seems almost certain that a change in sea level occurred at this time, changing the habitat to which many of these early animals were adapted, and driving them to extinction. Pherhaps climate change as well...?

Ordovicium Period (495-443 443 MY) a period of great diversification The Ordovician was named by the British geologist Charles Lapworth in 1879.

28 Ordovicium Period ( MY) a period of great diversification The Ordovician was named by the British geologist Charles Lapworth in He took the name from an ancient Celtic tribe, the Ordovices, renowned for its resistance to Roman domination. The boundary between the Cambrian and the Ordovician is marked by the appearance of certain planktic graptolites

The Ordovician (495-443 443 MY) Particularly good examples of Ordovician sequences are found in: China, Western Australia, Argentina, the United

Ordovician rocks over much of these areas are typified by considerable thickness of lime and other carbonate rocks that accumulated in shallow

29 The Ordovician ( MY) Particularly good examples of Ordovician sequences are found in: China, Western Australia, Argentina, the United States and Canada. Ordovician rocks over much of these areas are typified by considerable thickness of lime and other carbonate rocks that accumulated in shallow subtidal and intertidal environments. Rocks formed from sediments deposited on the margins of Ordovician shelves are commonly dark, organic-rich mudstones which bear the remains of graptolites and may have thin seams of iron sulfide. Graptolites are the most common fossils found in the mudstones.

30 Middle Ordovician continental plate configuration

The Ordovician Period - great radiation of life Ordovician strata are characterized by numerous and diverse trilobites and conodonts found in sequences of shale, limestone, dolostone, and sandstone.

31 The Ordovician Period - great radiation of life Ordovician strata are characterized by numerous and diverse trilobites and conodonts found in sequences of shale, limestone, dolostone, and sandstone. In addition, bryozoans, corals, crinoids, as well as many kinds of brachiopods, snails, clams, and cephalopods appeared for the first time in the geologic record in tropical Ordovician environments. Life in sediments developed witnessed by increased bioturbation of sediments. Mostly bivalves and trilobites. Lifeontheseafloor developed rapidly intense grazing, scavenging, predation and reef building. Starfishes arrive.

New groups of animals als arrive The Graptolites appear.

Most fossil graptolites look like nothing so much as tiny sawblades.

Graptolites are thought to have been planktonic, floating or slowly sinking through the water.

32 New groups of animals als arrive The Graptolites appear. For a long time no one was sure what kind of animals they were. Most fossil graptolites look like nothing so much as tiny sawblades. Wellpreserved graptolites can be seen to be tubular in cross-section. Graptolites are thought to have been planktonic, floating or slowly sinking through the water. The spiral shape of some was probably an adaptation to slow sinking. Other graptolites may have been connected to gas-filled sacs, keeping them buoyant. Very important stratigraphic markers due to rapid evolution.

GRAPTOLITES In structure they were stick like

Their preservation is quite often poor and usually

33 GRAPTOLITES In structure they were stick like organisms with an organic skeleton. In shape they could either be straight or curved, or possibly even spiral. Their preservation is quite often poor and usually just a carbonaceous film remain (hence their nam graptho: greek= write, lite: from greek, lithos= rock).

34 Kingdom Animalia, Phylum Protochordata Graptolithinia Graptolites planktic or benthic Appear as pencil- like marks on shale

Corals first appeared in Lower Ordovicium Sea anemones (sæfíflar) are closely related to Paleozoic corals, while jellyfish are distant relatives.

35 Corals first appeared in Lower Ordovicium Sea anemones (sæfíflar) are closely related to Paleozoic corals, while jellyfish are distant relatives. Coral is a very primitive animal consisting almost exclusively of a large stomach with an opening that serves both as mouth and anus. Corals dwell on the floor of shallow tropical seas.

36 Coral reefs Coral reefs are complex, enduring, magnificent and dynamic living structures of geologic proportion. They are among our planet s most prolific and intricately interrelated ecosystems. They are also the planet s oldest natural community. Today s reefs are simply the most recent link in a lengthy genetic chain.

37 The nautiloids (Álfasmokkar) The nautiloids, predecessors of present day squids and octopuses, evolve during the latest Cambrian and early Ordovician. They were highly successful predators

38 Some facts on cephalopods (hausfætlur, smokkar ) All are active marine predators, able to swim swiftly, and easily competing with fish in the marine habitat. There are 650 living species, but more than 7,500 fossil forms are known. Cephalopods are quite large by molluscan standards (6-70 cm), with the modern day Architeuthis, the giant squid, with a body length of up to 16 m the Ordovician nautiloid Cameroceras had a straight shell up to 10 metres in length and and the Cretaceous ammonoid Pachydiscus seppenradensis, with a coiled shell 3 metres in diameter The cephalopods are the largest invertebrates ever to live, with weights of one to two tons.

39 Cephalopods: : a major step towards more intelligent life... The tremendous evolutionary radiation of nautiloid cephalopods meant an increase in the level of intelligence in Paleozoic oceans. Cephalopods are the most intelligent of all invertebrates, owing to the development of elaborate manipulative organs (tentacles for touching and grasping). One researcher described the common octopus as like a sort of aquatic dog or cat. Although Ordovician cephalopods were probably not equal to modern forms in intelligence, they were certainly superior to that of contemporary (non-cephalopod) life-forms.

40 Ordovician sea floor

41 References, web resources etc Stanley, Earth System History,, chapter 12 Fortey, R. Life A natural History of the first four billion years of life on Earth. New York, Vintage Books, 346 pp. Fortey,, R. Trilobate Eywitness to Evolution.. London, Flamingo, 246 pp. nau.edu /~rcb edu/~devans/iitpw/science.html palaeos.com /Ordovician/Ordovician.htm toyen.uio no/palmus/galleri/blader/blad_x03.htm /Paleozoic_paleobiolog y.htm#ordovician edu/ordovician/ordovician.html

Chapter 12. Life of the Paleozoic

Chapter 12. Life of the Paleozoic Chapter 12 Life of the Paleozoic Paleozoic Invertebrates Representatives of most major invertebrate phyla were present during Paleozoic, including sponges, corals, bryozoans, brachiopods, mollusks, arthropods,