Geological History of Life Final Exam

Chordates

Includes 4 phylum: chordata, tunicata, conodonta, with cartilaginous rod-like notochord in dorsal position/cartilaginous axial skeleton, and phylum vertebrata, with bony or cartilaginous axial skeleton; vertebral column

phylum chordata (chordates)

early late cambrian-holoceneIncludes oldest chordates (yunanazoon, pikaia), marine, , evolved from arrow worms

Yunnanozoon

Earliest chordate, phylym chordata. Found in Chenxiang Fauna, Lower Cambrian. Elongate body, no well-defined head

Pikaia

Early chordate, phylum chordata, Burgess Shale, Middle Cambrian

phylum tunicata (aka ascidians) (chordates)

early late cambrian-holocene, includes Cheungkongella, solitary, rarely colonial, marine, benthic/attached, ocassionaly planktic, calcitic/aragonitic/fluoritic spicules fossils from miocene-holocene

Cheungkongella

Earliest tunicate (ascidian), Chenjian Fauna, attached to sea floor, early cambrian

phylum conodonta (chordates)

Late cambrian-triassic, had francolite teeth (conodonts), head with 2 large eyes, evolved from worms

Conodont elements

coniform, ramiform, pectinoform

coniform conodont

cone-like, simplest

ramiform conodonts

denticles (multiple cusps), basal cavity

pectinoform conodonts

basal cavity, basal pit, most complex

conodont chewing apparatus morphology

bilaterally symmetrical

Clydagnathus

Conodont animal (chordate, phylum conodonta) with head, lower carboniferous

phylum vertebrata (chordates)

Early cambrian-holocene, bony or rarely cartilaginous axial skeleton with vertebrae, head, and skull. Includes class agnatha, pisces, amphibia, reptilia, aves, and mammalia

class agnatha (phylum verbrata, chordates)

Early cambrian, ordovician-holocene, fishlike, jawless, marine, rarely freshwater. Modern lampreys and hagfishes

Class agnatha stratigraphical range (phylum vertebrata, chordates)

Paleozoic (ordovician-devonian)

Orders of class agnatha (phylum verbrata, chordates)

ostracoderms, thelodonts, heterostracans, osteostracans

Ostracoderm order (class agnatha, phylum vertebrata, chordates)

Ordovician-silurian, anterior bony plates, includes Sacambambaspis

Sacambambaspis

Lower ordovician, Bolivia, large plate-armoured filter feeder with eyes of the ostracoderm order (class agnatha, phylum vertebrata, chordate)

Thelodont order (class agnatha, phylum vertebrata, chordates)

Upper ordovician-devonian, covered with small scale-like sclerites, better swimmers, includes Loganella

Loganella

thelodont order (class agnatha, phylum vertebrata, chordates), lower Silurian, Scotland, covered with sclerites

Furcacauda

thelodont order (class agnatha, phylum vertebrata, chordates), lower Devonian, Canada,

heterostracan order (class agnatha, phylum vertebrata, chordates)

silurian-devonian, articulated anteropr bony plates, includes Drepanaspis

Drepanaspis

heterostracan order (class agnatha, phylum vertebrata, chordates), Germany, cephalic shield with ornamentation, benthic

Osteostracan order (class agnatha, phylum vertebrata, chordates)

late silurian-devonian, robust 1-piece cephalic shield, slow swimming, most abundant agnathan, includes Cephalaspis

Cephalaspis

Osteotracan order (class agnatha, phylum vertebrata, chordates), lower devonian, Scotland, 2 vibration sensorial zones

subphylum gnathostomata (phylum vertebrata, chordates)

middle silurian- holocene, organisms with jaws that evolved from agnathan acnestors: class pisces, amphibia, reptilia, aves, and mammalia

class pisces (subphylum gnathostomata, phylum vertebrata, chordates)

middle silurian - holocene, aquatic, gills/lungs, egg reproduction, flight in some cases, preserved as teeth (ichtolyites) and inner ear (otolith) fossils

subclass acanthodii (class pisces, subphylum gnathostomata, phylum vertebrata, chordates)

middle silurian-lower permian, oldest fishes (so oldest gnathostomata), “spiny sharks", cartilagionous skeleton, paired bony fins, small scales, includes Acanthodes, Diplacanthus, Gyracanthus

Acanthodes

subclass acanthodii (class pisces, subphylum gnathostomata, phylum vertebrata, chordates), lower permian, Germany

Diplacanthus

subclass acanthodii (class pisces, subphylum gnathostomata, phylum vertebrata, chordates), middle devonian, Scotland

Gyracanthus

subclass acanthodii (class pisces, subphylum gnathostomata, phylum vertebrata, chordates), upper carboniferous, UK, gigantism

Subclass placodermi (class pisces, subphylum gnathostomata, phylum vertebrata, chordates)

larte silurian-devonian, cephalic shield could cover the fins, most dominant fish in the devonian, composed of 2 groups: arthrodires and antiarchs

Arthrodires