Harding Sandstone Microfossils
Ordovician vertebrates are rare in the fossil
record, being known from only a few localities across the globe. The Middle
Ordovician Harding Sandstone of Colorado represents the oldest known vertebrate
bearing rocks in North America, and yet despite it’s age contains a surprisingly
diverse vertebrate fauna.
Charles Walcott first described the vertebrate fauna of the Harding Sandstone in
1892. At that time just two species were recognized:
Astraspis desiderata
and Eriptychius
americanum,
both of them primitive fish. The conodont fauna was described 40 years later and
additional species have slowly been identified since that time.
I have several specimens of each type available.
Photos are representative of the specimen you will receive.
Last Modified
08/27/2008
The majority of vertebrate fossils from the
Harding Sandstone are dermal plates and scales. The only teeth are those that
belong to the conodonts. All the fossils are microscopic, with most measuring
less than a millimeter. The known vertebrate fauna of the Harding Sandstone
consists of fish, shark and several species of conodont as listed below:
Fish - Agnathans
Astraspis desiderata
– known fromscales and articulated remains
Eriptychius
americanum
- known from scales and articulated remains |
Loganiid Thelodont fish
Unnamed
species – known only from scales |
Fish of uncertain affinities:
Skiichthyes
halsteadi - known only from scales
Undetermined fish scales |
Sharks
Unnamed
shark - known only from dermal denticles |
The specimens listed below
were obtained by breaking down the matrix of the Harding Sandstone in acetic
acid and collecting the fossils. One hundred pounds of sandstone produced less
than one cup full of fossil concentrate, indicating the rarity of this material.
All the specimens are microfossils, measuring on average ~1 mm long and are
housed in micropalaeontology well slides with aluminum cases and glass cover
slides. The cases and coverslides allow easy access to the specimen.
 |
|
Representative Specimens |
Name:
Astraspis desiderata -
Agnathan Fish
Geologic Age: Middle Ordovician
Stratigraphic detail: Harding Sandstone
Location: Colorado
Description: Dermal
Armor, 2 denticle types & armor plate
in one slide
Harding Sandstone Astraspis
- Price: $20.00
 |
|
Representative Specimens |
Name:
Eryptichius americanum -
Agnathan Fish
Geologic Age: Middle Ordovician
Stratigraphic detail: Harding Sandstone
Location: Colorado
Description: Dermal
Armor
Harding Sandstone Eryptichius
- Price: $10.00
 |
|
Representative Specimens |
Name:
Shark Denticles
Geologic Age: Middle Ordovician
Stratigraphic detail: Harding Sandstone
Location: Colorado
Description:
1 to 3 specimens of type 'A'
& type 'B' in one slide
Harding Sandstone Shark Denticles
- Price: $20.00
 |
|
Representative Specimens |
Name:
Undetermined Fish Denticle
Type "A" Pedestal
Geologic Age: Middle Ordovician
Stratigraphic detail: Harding Sandstone
Location: Colorado
Description:
1 to 3 specimens in one
slide
Harding Sandstone Fish Denticles "A"
- Price: $10.00
 |
|
Representative Specimens |
Name:
Undetermined Fish Denticle
Type "B" Button
Geologic Age: Middle Ordovician
Stratigraphic detail: Harding Sandstone
Location: Colorado
Description:
1 to 3 specimens in one
slide
Harding Sandstone Fish Denticles "B"
- Price: $20.00
 |
|
Representative Specimen |
Name:
Stereoconus robustus
Geologic Age: Middle Ordovician
Stratigraphic detail: Harding Sandstone
Location: Colorado
Description:
Conodont
Harding Sandstone Stereoconus
- Price: $10.00
 |
|
Representative Specimens |
Name:
Erismodus radicans
Geologic Age: Middle Ordovician
Stratigraphic detail: Harding Sandstone
Location: Colorado
Description: Conodont
Harding Sandstone Erismodus
- Price: $10.00
 |
|
Representative Specimens |
Name:
Chirognathus multidens
Geologic Age: Middle Ordovician
Stratigraphic detail: Harding Sandstone
Location: Colorado
Description: Conodont
Harding Sandstone Chirognathus Multi
- Price: $10.00
 |
|
Representative Specimens |
Name:
Chirognathus sp.
Geologic Age: Middle Ordovician
Stratigraphic detail: Harding Sandstone
Location: Colorado
Description: Conodont
Harding Sandstone Chirognathus sp.
- Price: $10.00
 |
|
Representative Specimens |
Name:
Ozarkodina concinna
Geologic Age: Middle Ordovician
Stratigraphic detail: Harding Sandstone
Location: Colorado
Description: Conodont
Harding Sandstone Ozarkodina
- Price: $10.00
 |
|
Representative Specimens |
Name:
Loganiid Thelodont
Geologic Age: Middle Ordovician
Stratigraphic detail: Harding Sandstone
Location: Colorado
Description: Fish Scale -
1 to 3
specimens in one slide
Harding Sandstone Loganiid
- Price: $10.00
 |
|
Representative Specimens |
Name:
Ptiloconus gracilis
Geologic Age: Middle Ordovician
Stratigraphic detail: Harding Sandstone
Location: Colorado
Description: Conodont
Harding Sandstone Ptiloconus
- Price: $10.00
 |
|
Representative Specimens |
Name:
Coleodus sp.
Geologic Age: Middle Ordovician
Stratigraphic detail: Harding Sandstone
Location: Colorado
Description: Conodont
Harding Sandstone Erismodus
- Price: $10.00