origin of vertebrates - indiana university bloomingtong404/lectures/lecture 2 - origin of...

Department of Geological Sciences | Indiana University (c) 2013, P. David Polly

G404 Geobiology

Shu et al., 1999

Reading: Benton Chap 1

Phylogeny and classification

Origin of vertebrates


G404 Geobiology

The next two labs will meet in the William R. Adams Zooarchaeology lab (12:20-2:15 pm)

Lab is located in the basement of the Student Building (Room 025)

A 1,400 square foot facility run by the Anthropology Department that includes over 10,000 modern comparative faunal remains.

Directed by Dr. Laura Scheiber, an Associate Professor in the Anthropology department, and managed by archaeology graduate student Matthew Rowe.

It is a privilege for G404 to be able to use the Zooarchaeology Lab facilities and specimens – please be careful with the skeletons and please leave the Lab as clean and orderly as you found it.

Zooarchaeology lab

(P.D. Polly)


G404 Geobiology

Class AgnathaLampreys and hagfish

Class ChondrichthyesSharks, rays and chimaeras

Class “Osteichthyes”Ray-finned and lobe-finned fish

Class AmphibiaFrogs, salamanders and gymnophonians

Class MammaliaMammals

Class “Reptilia”Lizards, snakes, crocodilians

Class AvesBirds

The phylogeny of living vertebrates

Reptilia

Amniota

Tetrapoda

Vertebrata


G404 Geobiology

Features commonly found in vertebrates

•Skeleton composed of cartilage or mineral tissue composed of hydroxyapatite in form of bone (with collagen matrix), dentine, and enamel

•Bilateral symmetry

•Head with multiple sense organs

•Brain and spinal cord (CNS, central nervous system)

•Skeleton supporting base of brain and body axis, usually elaborated more fully

•Segmented body axis with muscles

•Paired appendages

•Mouth, stomach, and gut

•Heart and circulatory system ventral to CNS

•Pharyngeal pouches with aortic arches (gill apparatus)


G404 Geobiology

Swalla and Smith, 2008.

Deuterostomes


G404 Geobiology

Living deuterostomes

Urchin (echinodermata) Acorn worm (hemichordata)

Pterobranch (hemichordata) Tunicates (urochordata)

Branchiostoma (cephalochordate)

Teleost fish (vertebrata)


G404 Geobiology

Phylogenetic relationships of living deuterostomes and their synapomorphies

Vertebrata

Cephalochordata

(Branchiostom

a)

Urochordata (tu

nicates)

Echinoderm

ata

Deuterostomia* blastopore becomes anus during development

Chordata* notochord* dorsal nerve tube* tail used for swimming* somites (segmented muscles)* neural tube with grey and white matter* shared patterns of developmental gene expression

Olfactores

Craniata * neural crest (tissue related to head development)* brain with eyes* paired olfactory capsules, semicircular canals

* di!use nerve network* tricoelomic development* muscular stalk* branched tentacular system

Hemichordata

* molecular sequence data

Ambulacraria


G404 Geobiology

Swalla and Smith, 2009

Timing of deuterostome divergencesBlack bars = known fossil occurrencesGrey bars = molecular clock estimates with error bars


G404 Geobiology

Today

Geo

logi

cal P

ast

Crown group A Crown group B

Stem group B

Stem group A

Crown groups and stem groupsCrown group - clade consisting of last common ancestor of the living members and all the descendants of that ancestor

Stem group - taxa more closely related to one crown group than another


G404 Geobiology

Shu et al, 1999, Nature, 402: 42-46.

Chengjiang (E. Cambrian)Many early deuterostomes

•525-520 Ma siltstones (Maotianshan Shales) from Yunnan

•10,000+ specimens, 90+ species

•Earliest good deuterostome fossils and oldest known true vertebrates

•UNESCO World Heritage site

Other important Cambrian Sites:•Burgess Shale, M. Cambrian, Alberta

•Wheeler Shale, L. Cambrian, North America


G404 Geobiology

Shu et al., 2001

Didazoon (a vetulicolian)Stem deuterostome (?)

• putative gill slits

• putative muscle segments

• putative endostyle


G404 Geobiology

Jefferies, 1984

Carpoids (=Calcichordates, Stylophorans)Stem Echinodermata (argued to be stem chordates by Jefferies)

• Ordovician through Devonian

• Calcitic, plated skeleton

• putative gill slits, putative tail


G404 Geobiology

Virtual fossil museum

Graptolites (Pterobranch-like Hemichordata)

Cambrian through Mississippian

• Colonial organism

• Skeleton composed of stipes with tubular structures that hold the individual animals


G404 Geobiology

Photo credit

ShankouclavaUnquestionable urochordate

• Branchial basket

• Esophagus, stomach and anus

• Endostyle

• receding tail?


G404 Geobiology

Shu et al., 1999, Nature, 402: 42-46,

Haikouichthys (=Myllokunmingia)Earliest craniate / vertebrate

• Mouth and gut tube

• Myotomes (muscle segments)

• Notochord

• Dorsal fin

• Gill pouches

• Heart

• Nasal and otic capsules


G404 Geobiology

Swalla and Smith, 2009

Fossil deuterostomes

1. Haikouichthys (L. Cambrian, craniate). 2. Cathaymyrus (L. Cambrian, cephalochordate). 3. Haikouella (L. Cambrian, chordate or stem craniate). 4. Rhabdopleura (M. Cambrian pterobranch hemichordate). 5. Stromatocystites (L. Cambrian, crown-group echinodermata). 6. Trochocystites (M. Cambrian, stem-group echinoderm). 7. Shankouclava (L. Cambrian, tunicate). 8. Phlogites (L. Cambrian, stem ambulacrarian). 9. Vetulicola (L. Cambrian, contested deuterostome affinities).


G404 Geobiology

Vertebrata

Cephalochordata

(Branchiostom

a)

Urochordata (tu

nicates)

Echinoderm

ata

Deuterostomia* blastopore becomes anus during development

Chordata* notochord* dorsal nerve tube* tail used for swimming* somites (segmented muscles)* neural tube with grey and white matter* shared patterns of developmental gene expression

Olfactores

Craniata * neural crest (tissue related to head development)* brain with eyes* paired olfactory capsules, semicircular canals

* di!use nerve network* tricoelomic development* muscular stalk* branched tentacular system

Hemichordata

* molecular sequence data

Ambulacraria


G404 Geobiology

Scientific papers for further readingJefferies, R. P. S. 1984. Locomotion, shape, and external ontogeny in some mitrate calcichordates. Journal of Vertebrate Paleontology, 4: 292-319.

Shu, D.-G., H.-L. Luo, S. C. Morris, X.-L. Zhang, S.-X. Hu, L. Chen, J. Han, M. Zhu, Y. Li, and L.-Z. Chen. 1999. Lower Cambrian vertebrates from south China. Nature, 402: 42-46.

Swalla, B. J. and A. B. Smith. 2008. Deciphering deuterostome phylogeny: molecular, morphological, and palaeontological perspectives. Philosophical Transactions of the Royal Society B, 363: 1557-1568.

origin of vertebrates - indiana university bloomingtong404/lectures/lecture 2 - origin of...

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