Cambrian Earth History

Transcription

1 Cambrian Earth History The Paleozoic Era Cambrian Plate Tectonics The Cambrian Explosion The Burgess Shale The Chengjiang Fauna h"p:// Copyright Greg Carter

2 The Paleozoic The Paleozoic is the earliest, and longest, era of the Phanerozoic Eon. The Cambrian is the earliest period of the Paleozoic. All animal phyla with good fossil records (including chordates) first appear during the early Paleozoic, with almost all appearing during the Cambrian. Only one such animal phylum appears acer the Cambrian (bryozoans appear in the Ordovician). The end of the Paleozoic is punctuated by the largest mass exfncfon in Earth s long history.

3 Cambrian Proterozoic Proterozoic- Cambrian boundary Fortune Head, SE Newfoundland Dr. G. M. Narbonne points to the earliest occurrence of Trichophycus pedum h"p:// wuerzburg.de/palaeontologie/stuff/casu11.htm Copyright (C) G. Geyer, 1997

4 Cambrian Plate Tectonics The Cambrian was a relatively quiet time for Laurentia, which drifted north toward the equator. The Avalon Island Arc, Baltica and Siberia were closing in on Laurentia, but wouldn t arrive until later in the Paleozoic. The Carolina Terrane was forming well to the south, near the part of Gondwana that would eventually become Namibia.

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6 The Cambrian Explosion animals without skeletons animals with skeletons Sudden appearance in the fossil record and rapid diversification of animals with hard parts

7 The Cambrian Explosion in Animal Diversity

8 Why??? Global Changes Fluctuating carbon isotopes Caused by changes in primary productivity? Difficult to interpret. Increase in oxygen Gradual increase continues, but no jump Increase 34 S Tied to redox, complex interaction of tectonic and biochemical controls. Difficult to interpret. Increase in phosphorite production Complex causality, tied to redox. Difficult to interpret.

9 Why??? Global Changes Rising sea level Increased amount of shallow water habitat Development of macro-predators Perhaps the skeletons were for protection. However, singlecelled protists also develop skeletons, and not all skeletons would have worked as armor. Dozens of theories have been proposed, but no single theory has emerged as good enough to accept. New data is constantly being collected, so stay tuned

10 Early Cambrian Period Tommotian and Adtabanian Stages small, shelly fauna (SSF) Small calcite and apatite shells, bits, pieces, and other skeletal elements While many clearly came from known groups (e.g., mollusks), most can t be assigned with certainty. Very abundant, global distribution. Basic Palaeontology. Benton M.J. & Harper D. 1997

11 Early Cambrian Period Tommotian and Adtabanian Stages small, shelly fauna (SSF) Insoluble residue of limestone samples with phosphatic tubes and sclerites of so-called "small shelly fossils". Late Tommotian, Malykan, Lena River, Siberia. Copyright (c) G. Geyer,

12 The Middle Cambrian World Burgess Shale Chengjiang Lagerstatten a fossil deposit of unusual quality, frequently soft parts are preserved. Greenland Three Tropical Lagerstatten

13 Middle Cambrian Lagerstatten Chengjiang Burgess Shale

14 Burgess Shale Algal Reef Occasional mudslides washed animals from oxygenated shallow water to anoxic basin

15 Burgess Shale Animals preserved as fossils Animals with hard parts

16 Stephen Mountain

17 Walcott Quarry

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19 Burgess Shale Fauna Included taxa that are obviously members of familiar groups as well as weird and wacky extinct groups

20 Phylum Arthropoda HUGE phylum Sidneyia Modern Isopod

21 Marella Canadapsis Phylum Arthropoda HUGE phylum

22 Echmatocrinus Early crinoid Komodo National Park, Indonesia Photographer: Ken Knezick Phylum Echinodermata Big phylum

23 Phylum Brachiopoda minor phylum in modern ocean Paleozoic diversity high Micromitra Inarticulate brachiopod Diraphora Articulate brachiopod

24 Sponges Vauxia Phylum Porifera large phylum

25 Phylum Annelida: Class Polychaeta Very large class of worms Candida

26 Ottoia Phylum Priapulida tiny phylum in modern ocean (~15 species)

27 Hyolithids Superclass Trilobitomorpha Very large arthropod superclass, extinct at end of Paleozoic Trilobites Incerta sedis Hyolithida Small group of what might have been mollusks, extinct at end of Paleozoic

28 The weirdest of the weird turn out to be relatives of the modern onychophorans, or velvet worms 1997 José A. Vargas Modern Phylum Onychophora 16 genera Aysheaia Hallucigenia

29 Hallucigenia Mary Parrish Reconstruction for the Smithsonian Museum of Natural History Hallucigenia

30 Other Burgess Shale taxa defy categorization Wiwaxia

31 Opabinia Other Burgess Shale taxa defy categorization

32 Burgess Shale Melodrama Copyright Greg Carter Greg Carter Editorial illustration for Science Fiction Age magazine

33 Opabinia Mary Parrish Reconstruction for the Smithsonian Museum of Natural History

34 Anomalocaris Other Burgess Shale taxa defy categorization

35 Anomalocaris

36 Anomalocaris Mary Parrish Reconstruction for the Smithsonian Museum of Natural History Anomalocaris

37 Phylum Chordata Big phylum including vertebrates Pikaia Amphioxus The Burgess Shale fauna includes this small cephalochordate, a relative of the earliest chordate

38 Chorus: It's a long way from amphioxus, it's a long way to us. It's a long way from amphioxus to the meanest human cuss. It's good-bye to fins and gill slits, and welcome lungs and hair. It's a long, long way from amphioxus, but we all came from there. Oh, a fish-like thing appeared among the annelids one day, It hadn't any parapods or setae to display. It hadn't any eyes or jaws or ventral nervous chord. But it had a lot of gill slits and it had a notochord. It wasn't much to look at and it scarce knew how to swim. And Nories was very sure it hadn't come from him. The Molluscs wouldn't own it and the Arthropods got sore. So the poor thing had to burrow in the sand along the shore. He burrowed in the sand before a crab could nip his tail. And he said, "Gill slits and myotomes are all to no avail." "I've grown some metapleural folds and sport an oral hood. But all these fine new characters don't do me any good." It's a Long Way From Amphioxus He sulked awhile down in the sand, without a bit of pep; Then he stiffened up his notochord and said, "I'll beat 'em yet!" "Let them laugh and show their ignorance, I don't mind their jeers." "Just wait until they see me in a hundred million years." "My notochord shall change into a chain of vertebra, And, as fins, my metapleural folds will agitate the sea." "My tiny dorsal nervous chord shall be a mighty brain. And the vertebrates shall dominate the animal domain."

39 The Chengjiang fauna is an earlier Burgess Shale-like fauna, predating the Burgess Shale by ~12 Ma.

40 The Chengjiang fauna added considerably to the bestiary of the Cambrian Explosion Porifera (sponges) Crumillospongia frondosa Walcott, Choia carteri Walcott, Hazelia palmata Walcott, Leptomitus zitteli Walcott, Tabakkawia lineata Walcott, Allantospongia mica Rigby & Hou, Choiaella radiata Rigby & Hou, Leptomitella metta Rigby, Leptomitus teretiusculus Chen, Hou & Lu, Paraleptomitella dictyodroma Chen, Hou & Lu, Parvulonoda dubia Rigby & Hou, Quadrolaminiella diagonalis Chen, Hou & Lu, Saetospongia densa Mehl & Reitner, Triticispongia diagonata Mehl & Reitner, Halichondrites confusus Dawson, Uncertain Affiliations Eldonia eumorphia Sun & Hou, Facivermis yunnanicus Hou & Chen, Rotadiscus grandis Sun & Hou, Xidazoon stephanus Shu, Conway Morris & Zhang, Dinomischus isolatus Conway Morris, Lobopodia Hallucigenia sparsa Walcott, Cardiodictyon calenudum Hou, Ramsköld & Bergström, Hallucigenia fortis Hou & Bergstöm, Luolishania conicruris Hou & Chen, Microdictyon sinicum Chen, Hou & Lu, Onychodictyon ferox Hou, Ramsköld & Bergström, Paucipodia inermis Chen, Zhou & Ramsköld, Algae Cambrorhytium major Walcott, Yuknessia simplex Walcott, Cinocylindrica yunnanensis Chen & Erdtmann, Megaspirella houi Chen & Erdtmann,

41 Yuknessia Green algae Marpolia Cyanobacteria

42 Xidazoon What is it? It s a whatsit like several Burgess Shale creatures.

43 The most amazing discoveries were the new arthropods (right) and the incredible chordates Chordates Cathaymyrus diadexus Shu et al. Cathaymyrus haikouensis Luo & Hu, Cheungkongella ancestralis Shu, Chen, Han & Zhang, Haikouella lanceolata Chen, Huang & Li, Haikouichthys eraicunensis Luo, Hu & Shu, Myllokunmingia fengjiaoa Shu, Zhang & Han, Yunnanozoon lividum Hou, Ramsköld & Bergström, Zhongxiniscus intermedius Luo & Hu, Peytoia nathorsti Walcott, Acanthomeridion serratum Hou, Chen & Lu, Almenia spinosa Hou & Bergström, Amplectobulua symbrachiaciata Hou, Bergström & Ahlberg, Anomalocaris saron Hou, Bergström & Ahlberg, Canadaspis laevigata Hou & Bergström, Chengjiangocaris longiformis Hou & Bergström, Cindarella eucalia Chen, Ramsköld, Edgecombe & Zhou, Fortiforceps foliosa Hou & Bergström, Fuxianhuia protensa Hou, Isoxys paradoxus Hou, Jianfengia multisegmentalis Hou, Kuamaia lata Hou, Kuamaia muricata Hou & Bergström, Leanchoilia illecebrosa Hou, Misszhouia longicaudata Zhang & Hou, Naraoia longicaudata Zhang & Hou, Naraoia spinosa Zhang & Hou, Odaraia? eurypetala Hou & Sun, Retfacies abnormalis Hou, Chen & Lu, Rhombicalvaria acantha Hou, Saperion glumaceum Hou, Ramskouml;ld & Bergström, Sinoburius lumaris Hou, Ramskouml;ld & Bergström, Skioldia aldna Hou & Bergström, Squamacula clypeta Hou & Bergström, Urokoida aequalis Hou, Chen & Lu, Xandarella spectaculum Hou, Ramsköld & Bergström, Yunnanocephalus yunnanensis Mansuy, 1912 Alacomenaeus cambricus Simonetta, Chuandianella ovata Li, Eoredlichia intermedia Lu, Isoxys auritus Jiang. Kuanyangia sp. Hupé, Wutingaspis tingi Kobayashi,

44 Yunnanozoon Oldest known hemichordate, sister group to the chordates

45 Cathaymyrus Oldest known cephalochordate, perhaps an older relative of Pikaia

46 Myllokunmingia Oldest known member of the vertebrate clade!!! The next known vertebrate appears in the fossil record 50 Ma later.