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Featured Fossil Archive: Graptolites

 

Pendograptus pendens - a graptolite with four serrated stipes

Fossil Type:

Graptolite

Name:

Pendograptus pendens Elles

Formation:

Bendigonian zone (Be3/4?)

Age:

Early Ordovician

Location:

Victoria, Australia

Notes:

This graptolite has four stipes from a point of attachment (nema). Graptolites are used as stratigraphic markers because they were pelagic and floated with ocean currents enabling them to settle to the sea floor over wide areas when they died. Anonymous collection. Scale = 2 cm

Date Posted:

February 26, 2014

 

Isograptus caducus imatatus - a pelagic graptolite from Australia

Fossil Type:

Graptolite

Name:

Isograptus caducus imatatus Harris

Formation:

Castlemainian zone Ca3

Age:

Early Ordovician

Location:

Bullengarook slate quarry, Victoria, Australia

Notes:

This odd-shaped graptolite is somewhat batlike in form. Graptolites serve as stratigraphic markers where they occur in some abundance (Australia and Europe in particular). Anonymous collection. Specimen is 1 cm wide.

Date Posted:

January 22, 2014

 

Unidentified dendritic graptolite

Fossil Type:

Graptolite

Name:

Unidentified dendritic graptolite

Formation:

Curdsville Member, Lexington Limestone

Age:

Lowermost Upper Ordovician

Location:

Garrard Co., Kentucky

Notes:

Graptolites of this growth form are thought to attach to a substrate on the seafloor rather than float (pelagic) like Geniculograptus and other simpler forms. They are also well-known in the Silurian and Devonian periods. Richard Schrantz specimen.

Date Posted:

December 11, 2013

 

Pendeograptus fruticosus graptolite from the Ordovician of Australia

Fossil Type:

Graptolite

Name:

Pendeograptus fruticosus (Hall)

Formation:

Bendigonian zone (Be3/4?)

Age:

Early Ordovician

Location:

Victoria, Australia

Notes:

This graptolite has three stipes from a point of attachment (nema). This is evolutionary positioned in layers between four-stipe graptolites (like Tetragraptus) to those with only two like Didymograptus. As such, they are important stratigraphic markers. Anonymous collection. Scale = 2 cm

Date Posted:

October 29, 2013

 

Pseudisograptus hastatus - a graptolite

Fossil Type: Graptolite
Name: Pseudisograptus hastatus (Harris)
Formation: Castlemainian zone Ca3
Age: Early Ordovician
Location: Bullengarook slate quarry, Victoria, Australia
Notes:

This odd-shaped graptolite is somewhat birdlike in form. Graptolites serve as stratigraphic markers where they occur in some abundance (Australia and Europe in particular). Anonymous collection. Specimen is 1 cm wide.

Date Posted: September 23, 2013

 

Geniculograptus sp.preserved in black carbon.

Fossil Type:

Graptolite

Name:

Geniculograptus sp. 

Formation:

Kope

Age:

Cincinnatian, Upper Ordovician

Location:

Danville, Boyle Co., Kentucky

Notes:

The most common graptolite in the Ordovician of the Ohio Valley is Geniculograptus. It is preserved in black carbon and has a straight stipe with thecae (the location of the individuals within this floating colony) facing inward. Rick Schrantz collection. Scale on the left.

Date Posted:

August 12, 2013

 

Carbonized dendritic graptolite from eastern Kentucky

Fossil Type:

Graptolite

Name:

Unidentified - Dendrograptus or Desmograptus?

Formation:

Bisher

Age:

Late Silurian

Location:

Lewis Co., Kentucky

Notes:

Carbonized graptolites are not unusual in the Silurian rocks in Kentucky. This is a dendritic form, likely attached to the sea floor (benthic) rather a pelagic floating form. Rick Schrantz specimen.

Date Posted:

July 1, 2013

 

Mass of the graptolite Geniculograptus typicalis - a carbonized fossil

Fossil Type:

Graptolite

Name:

Geniculograptus typicalis (Hall) 

Formation:

Kope

Age:

Cincinnatian, Upper Ordovician

Location:

Carroll Co., Kentucky

Notes:

Commonly observed as carbon imprints, as its name implies, it is widespread in the Upper Ordovician rocks. Mass deposits such as this are not unusual. Click here for a wider view. Click here for a view of the entire rock. Anonymous collection.

Date Posted:

April 24, 2013

 

Tetragraptus serra - an Early Ordovician graptolite with four stipes

Fossil Type:

Graptolite

Name:

Tetragraptus cf. T. serra (Brongniart)

Formation:

Bendigonian zone (Be3/4?)

Age:

Early Ordovician

Location:

Victoria, Australia

Notes:

This graptolite genus is widespread, occurring in the southern hemisphere in Argentina and Australia where it serves as a stratigraphic index fossil. ‘Tetra’ means four, the number of ‘stipes’ attached to the ‘nema’ or connecting point of this genus. Anonymous collection. Scale = 2 cm

Date Posted:

March 15, 2013

 

Phyllograptus is a leaf-shaped graptolite of the Ordovician period.

Fossil Type:

Graptolite

Name:

Phyllograptus sp.

Formation:

Castlemainian zone Ca1

Age:

Early Ordovician

Location:

Mia Mia, Victoria, Australia

Notes:

Named for is leaf-like shape, this graptolite was one of many pelagic forms that floated around in the Ordovician seas. This allowed widespread distribution, and rapid evolution of species enable graptolites to help with the correlation of  Ordovician rock layers over distance. It consists of a thin film of carbon on white shale. Anonymous collection. Scale = 2 cm.

Date Posted:

February 4, 2013

 

Fossil Type:

Graptolite

Name:

Isograptus victoriae maximodivergens Harris

Formation:

Castlemainian zone Ca3

Age:

Early Ordovician

Location:

Bullengarook Slate Quarry, near Gisborne, Victoria, Australia

Notes:

Graptolites are good stratigraphic markers because they were planktonic and evolved quickly. Isograptus is widely distributed around the world. As its name implies, this species is found in Victoria, Australia and “maximodivergens” indicates Harris (1933) described it was the widest divergent of that lineage. Anonymous specimen.

Date Posted:

December 30, 2012

 

Black carbon Dictyonema graptolites and white calcified bryozoans

Fossil Type:

Graptolite

Name:

Dictyonema sp.      

Formation:

Jeffersonville Limestone

Age:

Eifelian, Middle Devonian

Location:

Louisville, Jefferson Co., Kentucky

Notes:

Graptolites are not common in this formation, but are well-documented in the upper strata. Dictyonema is a benthic form that attached itself on the seafloor. These fossils typical occur ‘carbonized’ – with little detail preserved. These fragments are mixed with fenestrate bryozoans. View is about 15 cm. Falls of the Ohio State Park specimen.

Date Posted:

October 22, 2012

Graptolite Didymograptus spinulosus

Fossil Type:

Graptolite

Name:

Didymograptus spinulosus (Perner)    

Formation:

Unknown

Age:

Silurian

Location:

Checo, Guadaljara, Spain

Notes:

This genus is common in the Lower and Middle Ordovician rocks in Europe and North America (and apparently in the Silurian of Spain). It is a bifurcated form with a serrated edge. Anonymous collection.

Date Posted:

September 11, 2012

 

Oktavites spiralis is a coiled graptolite

Fossil Type:

Graptolite

Name:

Oktavites spiralis (Geinitz)      

Formation:

Unknown

Age:

Silurian

Location:

Checo, Guadaljara, Spain

Notes:

This is a widespread form in the Silurian rocks in Europe and beyond. As planktonic colonial organisms, they floated far and wide and are found in specific stratigraphic zones called a ‘biozone.’ Part / Counter-part from an anonymous collection.

Date Posted:

July 6, 2012

 

Fossil Type:

Graptolite

Name:

Desmograptus micronematodes (Spencer)        

Formation:

Waldron Shale

Age:

Wenlockian, Silurian

Location:

Sellersburg, Clark Co., Indiana

Notes:

While many graptolites were pelagic, floating with the currents, this was a colonialorganism attached to the seafloor. Graptolites are in phylum Hemichordata, class Graptolithinia living as early as the Cambrian and as late as the Mississippian (Lower Carboniferous). They are typically found, like this one, as carbon residue in sedimentary rock. Anonymous collection. Scale = 2 cm

Date Posted:

June 18, 2012

 

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Created June 25, 2012, Updated  February 28, 2014.