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Old 03-07-2014, 05:27 PM posted to sci.bio.botany
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First recorded activity by GardenBanter: Jul 2008
Posts: 12
Default A Fossil Flora From The Sharktooth Hill Bone Bed Formation

I've copied and pasted here the text (author is Robert E. Reynolds) from a
rather recent (2011) paper on the discovery of a unique, terrestrial,
predominantly land-laid fossil flora preserved within the marine middle
Miocene Temblor Formation--the same geologic rock deposit, of course, that
contains the world-famous Sharktooth Hill Bone Bed, exposed in the dusty
western foothills of the southern Sierra Nevada northeast of Bakersfield,
California, an incomparable marine bone bed that occurs within what
geologists call the Round Mountain Silt Member of the Temblor Formation, a
specific subunit dated rather precisely at 15.9 to 15.2 million years old.

The fossil plants described below by Mr. Reynolds, in my opinion (and
suggested by Reynolds, as well) occur below the actual Sharktooth Hill Bone
Bed, in strata that more closely resemble the underlying--and, hence
older--Olcese Sand Member of the Temblor Formation; Reynolds mentions a
lower middle Miocene horse specimen from the fossil plant bed that
characterizes a North American Cenozoic mammalian stage of closer to 17 to
16 million years old.

The quoted text, by the way, is from a compilation entitled "The 2011 Desert
Symposium Field Guide and Proceedings" California State University Desert
Studies Consortium April 2011. Edited by Robert E. Reynolds.

See my page "A Visit To The Sharktooth Hill Bone Bed, Southern California"
over at http://inyo.coffeecup.com/site/sb/sharkbonebed.html for details
regarding the world-famous Round Mountain Silt bone bed.

Quoted section follows, immediately below:

A new Miocene flora from the Round Mountain Silt
Robert E. Reynolds

Abstract

The Eagle Crest Flora is the first described flora from the Round Mountain
Silt
contains 18 taxa including algae, grasses, shrubs and trees gathered by
streams
that flowed through a riparian/aquatic community to deposit waterlogged
organic debris in a marine environment. A few taxa suggest a non-adjacent
coniferous woodland. The Eagle Crest Flora and associated bone bed contain
invertebrate and vertebrate fossils: marine mollusks, sharks, fish, mammals,
and
horse. The bone bed may be similar in age to, or older than the 15.5 Ma
Sharks
Tooth Hill Bone Bed. The flora is compared with other Miocene floras from
southern California.

Background

Residential development in the greater Bakersfield area
during 2006-2008 included construction excavation
in the Rio Bravo area along the south side of the Kern
River , central Kern County, California. Development
north of the Kern River Highway (SR-178) required
resource monitoring and salvage to protect significant,
non-renewable paleontological resources-fossils.
Paleontological resources

The Eagle Crest bone bed in the Miocene marine
Round Mountain Silt produced a minimum of 90
distinct taxa identified from more than 3,657 vertebrate
and non-vertebrate fossil specimens. Invertebrate taxa
include 16 species of pelecypods, 9 species of gastropods,
a scaphopod, pencil urchins, and crustaceans.
Marine vertebrates include seven taxa of fish, three
genera of rays, 19 shark taxa, a skate, and a sea turtle.
Mammals include Ten marine mammals and one land
mammal have been identified. A unique collection of
Miocene fossil plants with at least 18 species is associated
with the marine mollusks and marine mammals.

Eagle Crest Flora

The plant specimens collected during the monitoring
program at Eagle Crest are apparently the first fossil
plants to be described from the Round Mountain Silt,
and represent 18 new plant species. These plants were
probably washed from inland river banks and forested
hills by continental drainage systems that developed
distal back bays and deltas along the coast line. Mats
of leaves and small logs would drift to sea, become
waterlogged, and sink to depths in quiet ocean water
that contained seaweed and marine fossils. Some of the
logs became silicified, perhaps saturated with silica from
volcanic ash in marine silts. In most cases, leaves and
fronds are represented by spaces highlighted by brown
stains of pyrolusite. Miocene fossils recovered during
this study were associated with rounded pebbles and
cobbles that may help describe the rocks in the source
highlands east of the shoreline.

The intermittent stream system transporting the flora
had variable rates of flow, perhaps because of seasonal
climate or storms. The variable energy and carrying
capacity of the stream was sometimes great enough to
support logs, yet gentle enough to move fragile charcoal
and leaves at other times.

The preservation of leaves from different floral
habitats along with red algae (seaweed) and marine
mollusks sows that the stream carried plant debris from
a wide drainage area and deposited them in a quiet
marine environment.

Age of the Round Mountain Silt

Fossil deposits along the Pacific coast that allow comparison
of marine faunal events to continental fauna
and flora are rare. This is significant because it helps
compare the timing of marine and terrestrial events,
including the flora that was adjacent on the continent.
Magnetic stratigraphy and strontium-isotope dating
places the time of deposition of the Sharks Tooth Hill
bone bed at 15.5 Ma.

The Eagle Crest Bone Bed has more molluscan
taxa in common with the older, underlying Olcese
Sand than with the Lower or Upper Round Mountain
Silt, suggesting an earlier age. Alternatively,
a gray, glassy ash directly below the Eagle
Crest Bone Bed chemically resembles USGS sample
buf94-617, dated at15.2 Ma.

The Sharks Tooth Hill bone bed produces middle
Miocene land mammals representing the Barstovian
NALMA Fossils salvaged program from Eagle
Crest may be earlier. The scaphoid (wrist bone) of a
small Miocene horse associated with marine mammals,
mollusks, fish, and sharks compares favorably with that
of the small Miocene three-toed horse Archaeohippus
mourningi. The edges and margins of the proximal and
distal surfaces of articulation are sharp and unworn,
suggesting it was not reworked from older sediments
into this deposit. Archaeohippus sp. is constrained to
the late Hemingfordian and early Barstovian North
American Land Mammal Age (NALMA), between 17
and 15 Ma. The precise age of the Eagle
Crest Flora and bone bed remains undetermined.

Environment of deposition

The Eagle Crest locality contains Miocene fish, rays,
skates, and sharks which represent mid-ocean, nearshore,
surface, and bottom-dwelling species. The taxa
lived in open water, kelp beds, the surf zone, and rocky
habitats.

Like the fish, the Miocene marine mammals from
the Eagle Crest locality come from a variety of midocean
and near-shore marine habitats:. open water, kelp
beds, the surf zone, and rocky shores. Seals, sea lions,
and walrus live and raise young on the shore but seals
hunt in the ocean and walrus search for mollusks along
rocky shores. The desmostylid probably had habits like
a hippopotamus, living in salt, fresh, and estuarian
water and feeding on aquatic vegetation.

Plant habitats

Several habitat zones are represented by the Eagle
Crest plants. The red algae (seaweed) is restricted to a
marine coastal shoreline. Grasses and horsetails grow
along slow moving streams, ponds, and estuarian
deltas. Willow, birch and cottonwood are members
of the stream-side riparian community. Avocado and
mountain mahogany might be found on coastal slopes;
cypress and pine grow on higher hillsides. The presence
of palmetto, avocado, and magnolia indicate a
temperate climate. The plant association is similar to
other assemblages found in near-shore Miocene marine
deposits in southern California.

Geographic relationships of Miocene floras

The Eagle Crest Flora was deposited in a marine
environment, as indicated by associated mollusks, fish
and marine mammals, and is the only flora in Table B
associated with marine seaweed (red algae). The Eagle
Crest Flora may have been transported along streams
through a back bay before reaching the ocean, and
therefore includes two aquatic plant taxa, absent in
the other Miocene floras.

Summary

The Eagle Crest deposit produced a collection of plant
taxa deposited by streams. The streams probably passed
between lowland slopes into marine back bays. The
flora, with 18 plant species, is the first described from
the Round Mountain Silt. When compared to other
Miocene floras in Kern, Los Angeles and San Bernardino
Counties, it adds to the geographic picture of mid-
Miocene floras. The specimens have been curated into
the collections of the Buena Vista Museum of Natural
history under numbers CHO 0701, P0001 - P014.



  #2   Report Post  
Old 03-07-2014, 05:44 PM posted to sci.bio.botany
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First recorded activity by GardenBanter: Jul 2008
Posts: 12
Default A Fossil Flora From The Sharktooth Hill Bone Bed Formation

"Inyo" wrote in message
...

I've copied and pasted here the text (author is Robert E. Reynolds) from a
rather recent (2011) paper on the discovery of a unique, terrestrial,
predominantly land-laid fossil flora


More precisely phrased, this is a "predominantly land-derived fossil flora;"
the Miocene terrestrial plants occur in a marine geologic rock deposit.

preserved within the marine middle Miocene Temblor Formation--the same
geologic rock deposit, of course, that contains the world-famous Sharktooth
Hill Bone Bed, exposed in the dusty western foothills of the southern
Sierra Nevada northeast of Bakersfield, California, an incomparable marine
bone bed that occurs within what geologists call the Round Mountain Silt
Member of the Temblor Formation, a specific subunit dated rather precisely
at 15.9 to 15.2 million years old.

The fossil plants described below by Mr. Reynolds, in my opinion (and
suggested by Reynolds, as well) occur below the actual Sharktooth Hill
Bone Bed, in strata that more closely resemble the underlying--and, hence
older--Olcese Sand Member of the Temblor Formation; Reynolds mentions a
lower middle Miocene horse specimen from the fossil plant bed that
characterizes a North American Cenozoic mammalian stage of closer to 17 to
16 million years old.

The quoted text, by the way, is from a compilation entitled "The 2011
Desert Symposium Field Guide and Proceedings" California State University
Desert Studies Consortium April 2011. Edited by Robert E. Reynolds.

See my page "A Visit To The Sharktooth Hill Bone Bed, Southern California"
over at http://inyo.coffeecup.com/site/sb/sharkbonebed.html for details
regarding the world-famous Round Mountain Silt bone bed.

Quoted section follows, immediately below:

A new Miocene flora from the Round Mountain Silt
Robert E. Reynolds

Abstract

The Eagle Crest Flora is the first described flora from the Round Mountain
Silt
contains 18 taxa including algae, grasses, shrubs and trees gathered by
streams
that flowed through a riparian/aquatic community to deposit waterlogged
organic debris in a marine environment. A few taxa suggest a non-adjacent
coniferous woodland. The Eagle Crest Flora and associated bone bed contain
invertebrate and vertebrate fossils: marine mollusks, sharks, fish,
mammals, and
horse. The bone bed may be similar in age to, or older than the 15.5 Ma
Sharks
Tooth Hill Bone Bed. The flora is compared with other Miocene floras from
southern California.

Background

Residential development in the greater Bakersfield area
during 2006-2008 included construction excavation
in the Rio Bravo area along the south side of the Kern
River , central Kern County, California. Development
north of the Kern River Highway (SR-178) required
resource monitoring and salvage to protect significant,
non-renewable paleontological resources-fossils.
Paleontological resources

The Eagle Crest bone bed in the Miocene marine
Round Mountain Silt produced a minimum of 90
distinct taxa identified from more than 3,657 vertebrate
and non-vertebrate fossil specimens. Invertebrate taxa
include 16 species of pelecypods, 9 species of gastropods,
a scaphopod, pencil urchins, and crustaceans.
Marine vertebrates include seven taxa of fish, three
genera of rays, 19 shark taxa, a skate, and a sea turtle.
Mammals include Ten marine mammals and one land
mammal have been identified. A unique collection of
Miocene fossil plants with at least 18 species is associated
with the marine mollusks and marine mammals.

Eagle Crest Flora

The plant specimens collected during the monitoring
program at Eagle Crest are apparently the first fossil
plants to be described from the Round Mountain Silt,
and represent 18 new plant species. These plants were
probably washed from inland river banks and forested
hills by continental drainage systems that developed
distal back bays and deltas along the coast line. Mats
of leaves and small logs would drift to sea, become
waterlogged, and sink to depths in quiet ocean water
that contained seaweed and marine fossils. Some of the
logs became silicified, perhaps saturated with silica from
volcanic ash in marine silts. In most cases, leaves and
fronds are represented by spaces highlighted by brown
stains of pyrolusite. Miocene fossils recovered during
this study were associated with rounded pebbles and
cobbles that may help describe the rocks in the source
highlands east of the shoreline.

The intermittent stream system transporting the flora
had variable rates of flow, perhaps because of seasonal
climate or storms. The variable energy and carrying
capacity of the stream was sometimes great enough to
support logs, yet gentle enough to move fragile charcoal
and leaves at other times.

The preservation of leaves from different floral
habitats along with red algae (seaweed) and marine
mollusks sows that the stream carried plant debris from
a wide drainage area and deposited them in a quiet
marine environment.

Age of the Round Mountain Silt

Fossil deposits along the Pacific coast that allow comparison
of marine faunal events to continental fauna
and flora are rare. This is significant because it helps
compare the timing of marine and terrestrial events,
including the flora that was adjacent on the continent.
Magnetic stratigraphy and strontium-isotope dating
places the time of deposition of the Sharks Tooth Hill
bone bed at 15.5 Ma.

The Eagle Crest Bone Bed has more molluscan
taxa in common with the older, underlying Olcese
Sand than with the Lower or Upper Round Mountain
Silt, suggesting an earlier age. Alternatively,
a gray, glassy ash directly below the Eagle
Crest Bone Bed chemically resembles USGS sample
buf94-617, dated at15.2 Ma.

The Sharks Tooth Hill bone bed produces middle
Miocene land mammals representing the Barstovian
NALMA Fossils salvaged program from Eagle
Crest may be earlier. The scaphoid (wrist bone) of a
small Miocene horse associated with marine mammals,
mollusks, fish, and sharks compares favorably with that
of the small Miocene three-toed horse Archaeohippus
mourningi. The edges and margins of the proximal and
distal surfaces of articulation are sharp and unworn,
suggesting it was not reworked from older sediments
into this deposit. Archaeohippus sp. is constrained to
the late Hemingfordian and early Barstovian North
American Land Mammal Age (NALMA), between 17
and 15 Ma. The precise age of the Eagle
Crest Flora and bone bed remains undetermined.

Environment of deposition

The Eagle Crest locality contains Miocene fish, rays,
skates, and sharks which represent mid-ocean, nearshore,
surface, and bottom-dwelling species. The taxa
lived in open water, kelp beds, the surf zone, and rocky
habitats.

Like the fish, the Miocene marine mammals from
the Eagle Crest locality come from a variety of midocean
and near-shore marine habitats:. open water, kelp
beds, the surf zone, and rocky shores. Seals, sea lions,
and walrus live and raise young on the shore but seals
hunt in the ocean and walrus search for mollusks along
rocky shores. The desmostylid probably had habits like
a hippopotamus, living in salt, fresh, and estuarian
water and feeding on aquatic vegetation.

Plant habitats

Several habitat zones are represented by the Eagle
Crest plants. The red algae (seaweed) is restricted to a
marine coastal shoreline. Grasses and horsetails grow
along slow moving streams, ponds, and estuarian
deltas. Willow, birch and cottonwood are members
of the stream-side riparian community. Avocado and
mountain mahogany might be found on coastal slopes;
cypress and pine grow on higher hillsides. The presence
of palmetto, avocado, and magnolia indicate a
temperate climate. The plant association is similar to
other assemblages found in near-shore Miocene marine
deposits in southern California.

Geographic relationships of Miocene floras

The Eagle Crest Flora was deposited in a marine
environment, as indicated by associated mollusks, fish
and marine mammals, and is the only flora in Table B
associated with marine seaweed (red algae). The Eagle
Crest Flora may have been transported along streams
through a back bay before reaching the ocean, and
therefore includes two aquatic plant taxa, absent in
the other Miocene floras.

Summary

The Eagle Crest deposit produced a collection of plant
taxa deposited by streams. The streams probably passed
between lowland slopes into marine back bays. The
flora, with 18 plant species, is the first described from
the Round Mountain Silt. When compared to other
Miocene floras in Kern, Los Angeles and San Bernardino
Counties, it adds to the geographic picture of mid-
Miocene floras. The specimens have been curated into
the collections of the Buena Vista Museum of Natural
history under numbers CHO 0701, P0001 - P014.





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