GRAPTOLITES Flashcards
are an extinct group of marine, colonial animals that built a skeleton from a variety of proteins dominated by collagen
Graptolites
the individual cups in which the zooids lived
Theca
possibly containing the female zooid
Autotheca
possibly containing the male zooid
Bitheca
encloses the main stolon
Stolotheca
the branch of the theca
Stipe
use to attach itself in the seafloor
Holdfast
is the whole graptolites skeleton
Rhabdosome
transverse or oblique skeletal structures
Dissepiments
existed from the Middle Cambrian to the Lower Carboniferous
-found living in shallow water
-need a firm substrate on which to anchor
-attached their colonies to the ocean floor by a root-like base
-built branches, or stipes, made of several types of cups, or thecae, in which the zooids lived
Order Dendroidea
-existed from the Lower Ordovician to Lower Devonian
-most likely having evolved from a planktonic dendroid ancestor
-characterized by the development of a prominent thread-like nema extending from the sicula
-widely distributed around the globe during the Early Paleozoic
-hydrodynamic to stay afloat and in the correct orientation with respect to food-bearing currents
Order Graptoloidea
A thin tube and extension of the sicula, possibly used to attach to a floating object
Nema
Individual cup in which one zooid lived
Theca
A branch of the rhabdosome
Stipe
Part where the zooid protruded through the skeleton, in order to filter feed
Aperture
Conical tube secreted by the first member of the colony
Sicula
Spine at the end of the sicula
Virgella
Where the first zooid protruded through the skeleton
Aperture of Sicula
thecae are growing vertically upwards from the sicula
Scandent
thecae are added growing upwards at an angle/sideways
Reclined
the thecae are added outwards from the sicula
Horizontal
thecae are added growing downwards at a sideways
Declined
the thecae are added downwards from the sicula
Pendent
Different Thecal Types
Glyptograptid
Dicranograptid
Climacograptid
Hooked Monograptid
Enrolled
Cambrian Period (541-485 million years ago):
Graptolites first appeared.
Dominant fauna included trilobites and brachiopods.
Ordovician Period (485-443 million years ago):
Graptolites diversified.
Diverse marine invertebrates thrived.
Silurian Period (443-419 million years ago)
Graptolites evolved complex forms.
Early jawed fish and terrestrial plants emerged.
Devonian Period (419-359 million years ago):
Graptolite diversity declined.
Fish and early amphibians dominated.
Carboniferous Period (359-299 million years ago)
Graptolites went extinct.
Dominant fauna included terrestrial arthropods and early reptiles.
They formed delicate, three-dimensional mesh-like colonies used for filter-feeding.
Dictyonema graptolites were prominent during the Silurian and early Devonian periods (443-395 million years ago).
They are valuable index fossils for dating rock layers and studying past marine ecosystems.
DICTYONEMA
They had a distinctive Y-shaped or forked structure, resembling the letter “Y.”
Didymograptus graptolites were prevalent during the Ordovician and Silurian periods, from approximately 485 to 419 million years ago.
Valuable index fossils for dating rock layers and studying ancient marine ecosystems.
Variations in the Y-shaped branches are significant for understanding the evolution and diversity of graptolites.
DIDYMOGRAPTUS
They had a straight or slightly curved main axis with four lateral branches (stipes), giving them their name.
Tetragraptus lived during the Ordovician and Silurian periods (approximately 485 to 443 million years ago).
Valuable index fossils for dating rock layers and studying past marine ecosystems.
Showed variations in colony structure, aiding in the understanding of graptolite evolution.
TETRAGRAPTUS
They formed colonies with distinctive bifurcating, Y-shaped branches.
Predominant during the Silurian period (approximately 443 to 419 million years ago).
Valuable index fossils for dating rock layers and studying past marine ecosystems.
Variations in colony structures aid in understanding the evolution of graptolites.
DICRANOGRAPTUS
These graptolites formed colonies with branching structures that resembled small trees or shrubs.
They were primarily present during the Silurian period, which occurred from around 443 to 419 million years ago.
CLIMACOGRAPTUS
These graptolites formed colonies with branching structures that resembled small trees or shrubs.
They were primarily present during the Silurian period, which occurred from around 443 to 419 million years ago.
CYRTOGRAPTUS
They formed slender, elongated colonies with distinct characteristics.
Predominant during the Ordovician period, approximately 485 to 443 million years ago.
BOHEMOGRAPTUS
These graptolites are typically small and exhibit a curved or coiled structure.
They have notably large, thin thecae (individual compartments) that are isolated from each other.
The entire rhabdosome (the main stem or axis of the colony) of Rastrites is usually less than 4 cm in length.
The thecae of Rastrites can be quite long, reaching up to 2 cm, and often feature hooks or hoods at the apertures, which are the openings of the compartments.
RASTRITES
The earliest graptolites lived on the sea bed (a and b) while later forms were free floating
