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A. INDEX FOSSILS

• significant Silurian radiation
• late in Silurian or Early Devonian the last important order added (Terebratulida)
• rhynchonellides expanded
• reduction in inarticulates, orthids, and strophomenids
• most abundant Paleozoic Phyla
• pentamerids, orthids, rhynchonellids, and strophomenids dominant
• pentamerids most characteristic brachiopod
• robust tear-drop-shaped shell
• set of internal walls that show as clefts in internal molds

• Rugose
• insert new septa at only four locations during growth
• expansion after initial occurrence in the Ordovician
• only small rugose corals in Lower Silurian, increase and size and diversity afterward
• Tabulate
• colonial
• often reef building
• tabulae
• Lower Silurian tabulates also small, as were rugose
• dominant corals of the Silurian

B. OTHER INVERTEBRATES

• crinoids and blastoids
1. first crinoidal limestone
2. cystoids in decline
3. blastoids first appearance in Silurian
4. crinoids undergo radiation
• echinoids not common

• evolved in Ordovician
• some scavangers and many active carnivores, major predators of the time
• little mineralization in carapace
• four eyes, two large, rounded eyes on sides of the head (prosoma) and two small eyes on the middle of the top of the prosoma
• single pair of pincers, five pairs of legs behind pincers and on prosoma
• rear appendages shaped like paddles
• 13 body segments and rudderlike tail
• most a few inches but up to 9' long
• Range: Ordovivian-Permian

4. Bryozoans

• Trepostomes (stony bryozoans forming massive zoaria with elongate autozooecia) among dominant (slick-like or dome-like)
• abundant in Silurian
• contributed to reef framework

• undergo recovery and radiation
• significant stratigraphic utility limited to Ordo. and Silurian
• 32 European graptolite zones

• straight (orthocone) and curved (cyrtocone) dominated and became larger

7. Trilobites- no longer important stratigraphic indicators as they were in the Cambrian and Ordovician.

C. REEF FORMERS

• reefs extensive worldwide in shallow, tropical seas
• tabulate corals
• rugose corals-
• stromatoporoids-more common in high energy environment
• algae
• bryozoans- subordinate part of the reef fabric and assisted in binding the sediment

D. VERTEBRATES

• most Silurian fish were freshwater inhabitants
• three new orders of bony jawless fish (ostracoderms)
• first jawed fish (acanthoddians)
• fresh water
• numerous fins (paired) supported by sharp spines
• scales

E. LAND PLANTS

• first vascular plants in the Late Silurian

F. SOME MAJOR GENERA TO BE SEEN ON TENN.- KY.-IND. FIELD TRIP (page numbers from Moore, Lichlicher, and Fisher)

• Porifera
1. Stromotoporoids
2. Astraeospongia ("basket sponge') (p. 88,91)
• Tabulate Corals
• Favosites (honeycomb coral) (p. 116,131)
• Halysites abyrinthicus (chain coral) (p. 115,116)
• Syringopora (organ-pipe coral) (p. 115,116)
• Emmonsia (p. 131)
• Rugose Corals
• Entelophyllum (organ-pipe coral) (p. 125)
• Arachnophylum (p. 124)
• Arthropods
1. Calymene (trilobite) (p. 481)
• Gastropods
1. Platyostoma (p. 302)
• Crinoids
1. Eucalyptocrinites (p. 638)
2. Caryocrinus
3. Liriocrinus
4. Proteus
• Cystoids
1. Caryocrinites (p. 591-594)
• Blastoids
• Brachiopods
1. Pachydictya
2. Pentamerus (p. 237,239)
3. Rhipidium (p.239)
4. Spirifer eudora
• Nautiloid Cephalopods
1. Dawsonoceras

A. INDEX FOSSILS

• Atrypids, spifierids, and strophomenids dominant
• continued expansion until major Late Devonian extinctions (e.g. pentameridies)
• spiriferids abundant and reached their peak
1. lophophores arranged in a pair of spirals
2. very long hinges, resemble a pair of wings

• Tabulate and Rugose
• Peak of tabulate diversity in the Middle Devonian
• Beginning of peak in rugose diversity

• Cystoporates, Fenestrates,and Trepostomes dominant
• Stony bryozoans (Trepostomes) were abudant as they were in the Ordovician
• stick-like or globular zoaria

B. OTHER INVERTEBRATES

1. first true spiders
2. first spider mites (plant suckers)
3. Ammonoid cephalopods first appeared in Early Devonian
• ammonoids take over dominance from nautiloids
• ammonoids mostly goniatitic suture pattern
4. bivalves and gastropods greatly outnumbered by brachiopods
5. cephalopods declined
6. blastoids reached maxiumum abundance and distribution

C. REEF FORMERS

D. VERTEBRATES

1. first sharks, first true jaws which developed from gill arches, cartilagenous skeleton, exposed gill openings .
2. acanthodians disappeared
3. placoderms evolved
• heavily armoured
• evolved in fresh water and invaded sea toward end of period
• few survived end of the period
4. first true bony, ray-finned fish:
• bony skeleton
• five gill slits covered by an operculum
• swim bladder
• modest success in period but dominate Mesozoic and Cenozoic
5. greatest success of lungfish (3 living genera)
6. lobe-finned fish
• most fresh water
• coelacanth invaded oceans (one living genus)
Amphibians: first appeared late in the Devonian

E. LAND PLANTS

A BRIEF SUMMARY OF MAJOR ORDOVICIAN-DEVONIAN STEPS IN PLANT EVOLUTION

• The oldest fossils reveal evolution of non-vascular plants by the middle to late Ordovician Period (~450-440 m.y.a.) on the basis of fossil spores.
• These first non-vascular, "amphibious" plants, were limited primarily to lowland, wet areas, of temperate to tropical latitudes. Still most land areas were barren.
• By some 420 m.y.a., seedless vascular plants evolved which were bigger and more diverse than their ancestors. These seedless vascular plants required water for sperm to reach the eggs and were still limited in their distribution to wet climates. These seedless plants grew to tree size, reaching 10 or more meters by the late Devonian (~370 m.y.a.). Lowland swampy environments had abundant seedless plants.
• After the 1st land plants evolved (approximately 450 m.y.a.) they underwent rapid expansion and radiation with great forests by Middle Devonian Period. (385 m.y.a.). Although these forests were limited in their extent, vast quantities of organic material were deposited and preserved in swampy environments. Through time and burial, this organic material was converted to coal, forming the first significant coal deposits of Earth history.
• At a similar time (late Devonian, ~375-360 m.y.a.), seed bearing gymnosperm plants (non-flowering) evolved. The development of the seed allowed plants to proliferate and spread to drier areas of continents. Gymnosperms became the dominant plant type between ~290 to 145 m.y.a. and are still common today.
SEEDLESS PLANTS

• Psilopsids
1. sporangium and dichotomous stems
2. grew in bogs
3. most primitive seedless plants,
4. most lack roots and leaves,
5. simple vascular system,
6. abundant only in Devonian.
• Lycopsids
1. huge trees of coal forests (up to 30m).
2. Arose in the Early Devonian (small), large by Late Devonian
3. Lepidodendron - scale trees
4. Sigillaria - scale trees
5. During the Carboniferous, coal swamps with abundant trees of this type accumulated, forming the greatest coal deposits of all geologic time.
6. Elongate leaves emerged directly from trunks and branches, leaving distinctive leaf scars (shown in class).
7. Living club moss a representative
8. In many, sporangia in clusters called cones, male and female cones on separate plants (advantage for variability)

F. EXTINCTIONS

• 50% of all invertebrate genera at end of the period
• Warm-water invertebrates hit hardest
• extinctions over 5 m.y.

G. SOME MAJOR GENERA TO BE SEEN ON TENN.- KY.-IND. FIELD TRIP

• Porifera
1. Hydnoceras (p. 88, 91)
2. Hindia (p. 87,93)
3. Stromatoporoids
• Amphipora ramosa (branching stromatoporoid)
• Tabulate Corals
1. Emmonsia ramosa (colonial, honey-comb coral) (p. 131)
2. Syringopora (colonial) (p. 115,116)
3. Favosites hemisphericus turbinatus (colonial) (p. 116,131)
4. Favosites hemisphericus cornutiformis (ham hock coral)
5. Striatopora (colonial, finger coral) (p. 116,135)
6. Pleurodictyum (honey-comb or wasp-nest coral) (p. 129)
7. Alveolites (honey-comb coral) (p. 116)
8. Chaetetes (p. 113, 135)
• Rugose Corals
1. Siphonophrentis giganteas (giant, colonial, horn coral) (p. 125, 127)
2. Hexagonaria (colonial, honey comb coral) (p. 131-138)
3. Billingsastraea (colonial) (p.131)
4. Homalophyllum (p. 125, 127, 133)
5. Cystiphyllum (non-septate cup coral) (p. 123, 125, 138)
6. Trachypora (p. 131)
7. Zaphrenthis phrygia((p. 125, 127,135)
8. Heliophyllum
9. Heterophrentis
10. Scenophyllum
11. Blothrophyllum
12. Aulacophyllum
13. Eridophyllum
• Brachiopods
1. Paraspirifer acuminatus (p. 256)
2. Brevispirifer gregarius (p. 256)
3. Chonetes (p. 248, 250)
4. Atrypa (p. 212, 217, 251-254)
5. Platyrachella
• Pelecypod
1. Conocardium (p. 416)
2. Aviculopecten
• Gastropods
1. Turbonopsis (p. 302)
2. Bembexia
• Trilobites
1. Dalminites (p. 490, 491, 514, 519)
2. Proteus (p. 509)
3. Phacops rana
• Crinoids
1. Dolatocrinus (p. 641)
• Blastoids
1. Heteroschisma
2. Elaeacrinus
• Bryozoans
1. fenestrate