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Types of Graptolites in Cambrian-Ordovician and their Environmental Significance

By:

Abdullah Alqubaleeg201304210@kfupm.edu.sa

KFUPMEarth Science Department

Mar. 8, 2015

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Outline• Introduction.• Linnaean system for Graptolites.• Graptolite morphology.• Selective Graptolites• Environmental Significance• Conclusion.

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Introduction• Fossils provide information on geological time, evolutionary history,

and ancient environments.

• Graptolites are an extinct group of marine, colonial animals that

built their skeletons from a variety of proteins.

• They varied in colony size from 2 mm to over 1 m in length, and

in form from simple sticks to complicated bushy shapes.

• Graptolites are considered as excellent index fossils because of

their reputation for being distributed worldwide.

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Objectives• To discuss the origin and types of Graptolites, from Cambrian to

Ordovician.• To discuss some of their environmental significance.

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Modern Biological classification

Labspaces, March 26, 2011

Incr

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(Carolus Linnaeus),

All organisms grouped into five Kingdoms (Boggs,1995)

~90 phyla

Millions

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Hierarchical linnaean system for GraptolitesHemichordata

(Phylum)Enteropneusta(Class)

Graptolithina(Class)Dendroidea(Order)

Graptoloidea(Order)

Tuboidea(Order)

Camaroidea(Order)

Stolonoidea(Order)

Crustoidea(Order)

Planctosphaeroi-dea(Class)

Pterobranchia(Class)

Graptolites (Extinct)

(Mu,1987; Wikipedia, 2015)

Animalia(Kingdome)

Deuterostomia(Superphylum)

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Graptolite Classification

•Frech 1897•Mu 1950, 1973•Mu & Zhan 1966•Bulman 1955•Obut 1955, 1964•Jannmusson 1960, 1965•Bulman 1963b, 1970•Yu & Fang 1979•Lapwroth 1879, 1880

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Graptolite hard-part morphology

Orientation of a Graptolite Stipe.(Milsom, 2013)

Dendroid. Graptoloid

Different thecal types of Graptolites

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Benthic and Planktic diversity

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Plan

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(Milsom, 2013)

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Selective GraptolitesCo

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More >> Graptolites| Earth Lab Database

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Environmental Significance

• Graptolites are useful in biostratigraphy to date and correlate

Paleozoic rocks. For instance Hanadir and Ra’an members

• The paleogeographic, distribution of graptolites is useful for

biogeographic interpretations and plate tectonic reconstructions.

• The occurrence of graptolite-rich rocks is an important record of

shelf margin development and of oceanographic conditions in seas

above shelf margins.

• Graptolites provide a promising tool for recognizing maximum

flooding surfaces.

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Conclusion• Graptolithina, a class of Hemichordata, comprises chiefly six orders

known as Dendroidea, Graptoloidea,Tuboidea,Camaroidea, Stolonoidea and Crustoidea.

• Graptolites stared to form in the Middle Cambrian, increased in the early Ordovician and became extinct in the mid-Devonian.

• Graptolites are considered as excellent index fossils because of their reputation for being distributed worldwide.

• Graptolites are useful in biostratigraphy to date and correlate Paleozoic rocks. Besides, they are useful for biogeographic interpretations, plate tectonic reconstructions, oceanographic conditions and recognizing maximum flooding surfaces.

• Graptolites were found in Hanadir and Ra’an members of Qasim formation in Saudi Arabian, and Sahmah, Hasirah, and Saih Nihayda formations in Oman.

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References• Berry, W. B. (1962). Graptolite occurrence and ecology. Journal of Paleontology, 285-

293.• Egenhoff, S., & Maletz, J. (2007). Graptolites as indicators of maximum flooding

surfaces in monotonous deep-water shelf successions. Palaios, 22(4), 373-383.

• Finney, S. C., & Berry, W. B. (1997). New perspectives on graptolite distributions and their use as indicators of platform margin dynamics. Geology, 25(10), 919-

922.• Le Hérissé, A., Al-Ruwaili, M., Miller, M., & Vecoli, M. (2007). Environmental changes

reflected by palynomorphs in the early Middle Ordovician Hanadir Member of the Qasim Formation, Saudi Arabia. Revuede micropaléontologie, 50(1), 3-16.

• Maletz, J. (n.d.). Graptolites. University at Baffalo. Retrieved March 5, 2015, from http://www.glyfac.buffalo.edu/Faculty/jorgm/WebJorg07/malgraps.htm

• McKerrow, W. S., & Scotese, C. R. (Eds.). (1990). Palaeozoic palaeogeography and biogeography.

• Milsom, C., & Rigby, S. (2013). Fossils at a Glance. John Wiley & Sons.• Mu, A. T. (1987). Graptolite taxonomy and classification. Bulletin of the Geological

Society of Denmark, 35(3-4), 203-207.