Life on land in the Paleozoic

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Malcolm Conley
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1 Life on land in the Paleozoic Paleozoic Terrestrial Life: Some highlights First life on land probably Ordovician (or maybe even earlier), but not abundant until Silurian History of land (i. e., vascular) plants. Plants, coal, glaciation, and atmosphere History of insects History of terrestrial vertebrates (tetrapods) 1

2 Paleozoic Terrestrial Life: Some highlights First life on land probably Ordovician (or maybe even earlier), but not abundant until Silurian History of land (i. e., vascular) plants. Plants, coal, glaciation, and atmosphere History of insects History of terrestrial vertebrates (tetrapods) Highlights of vascular plant evolution Oldest definite vascular plant: Late Silurian Oldest seed: Middle Devonian Changing dominance of different groups Coal swamps dominated by lycopods, ferns, and sphenopsids: Carboniferous Dominance of conifers and cycads: Triassic-Jurassic First flowers: Early Cretaceous 2

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4 The Rhynie Chert (Scotland) Rhynia Specimen of Cooksonia pertoni with sporangia, from the Silurian of Shrewsbury, England. Image from Cooksonia fossil specimen (L) and reconstruction (R). Both Images from 4

Early Devonian landscape, painting by Zdenek Burian www.

5 Early Devonian landscape, painting by Zdenek Burian 5

6 The Gilboa Forest, Gilboa, Schoharie Co., NY -- Eospermatopteris, a seedfern and one of the earliest trees The origin of seeds 6

7 Archeopteris, an early seed fern (progymnosperm) 7

8 SPHENOPSID LYCOPOD TREE FERNS

9 Lycopods Lepidodendron Stigmaria Living lycopods Sphenopsids Calamites Modern horsetails 9

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13 Carboniferous coals in cyclothems 13

14 Paleozoic Terrestrial Life: Some highlights First life on land probably Ordovician (or maybe even earlier), but not abundant until Silurian History of land (i. e., vascular) plants. Plants, coal, glaciation, and atmosphere History of insects History of terrestrial vertebrates (tetrapods) 14

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Plants, coal, glaciation, and atmosphere History of insects History of terrestrial vertebrates

17 Paleozoic Terrestrial Life: Some highlights First life on land probably Ordovician (or maybe even earlier), but not abundant until Silurian History of land (i. e., vascular) plants. Plants, coal, glaciation, and atmosphere History of insects History of terrestrial vertebrates (tetrapods) The oldest known insect Rhyniognatha hirsti Rhynie Chert Early Devonian, Scotland Engel & Grimaldi, Nature, 427, Feb

18 Carboniferous Insects Meganeura Cockroach 18

19 Paleozoic Terrestrial Life: Some highlights First life on land probably Ordovician (or maybe even earlier), but not abundant until Silurian History of land (i. e., vascular) plants. Plants, coal, glaciation, and atmosphere History of insects History of terrestrial vertebrates (tetrapods) 19

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21 A, Acanthostega; - Late Devonian B, Ichthyostega; - Late Devonian C, Tulerpeton; - Late Devonian D, Loxommatidae; - Carboniferous E. Crassigyrinus; - Carboniferous F, Anthracosauroidea; - Carbaniferous to Triassic G. Amniota (including Seymouriamorpha); - Carb-Recent H, Aistopoda; - Carboniferous I, Nectridea; - Carboniferous to Permian J, Colosteidae; - Carboniferous K, Capitosauroidea; - Carboniferous to?cretaceous L, Lissamphibia. - Triassic to Recent Nested taxa and selected synapomorphies (unique characteristics): 1, Tetrapoda (limbs with digits, sacrum, fenestra ovalis, hyomandibula modified into a stapes); 2, reduced gill apparatus; 3, cleithrum free from scapulocoraroid, five digits in hind limb; 4, Neotetrapoda (five digits or less in both fore and hind limbs); 5, Reptiliomorpha (retractor pit for eye muscles); 6, loss of post-temporal fosas; 7, incipient pterygoid flange, phalangeal (finger/toe) formala of pes is 2, 3, 4, 5, 5, diplospondylous vertebrae, stapes sound-conducting; 8, Amphibia (four-digit manus); 9, large interpterygoidian vacuities; 10. Temnospondyli ('waisted' humerus, strap-like occipital condyle 21

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23 Two reconstructions of Acanthostega Primitive Amniotes (Reptiles) Seymouria, Late Permian Hylonomus, Early Pennsylvanian (the earliest known reptile) 23

24 Terrestrial Tetrapod Diversity (after Benton, 1985) 24

Adjustments to Life in Air

1 Adjustments to Life in Air Plants and Animals no buoyancy, need skeletal support desiccation physical-chemical environmental extremes (temperature, humidity, salinity) no nutrients in air reproductive