Species Diversity Lab Report
Species diversity of lithified samples from the Pliocene Jackson Bluff formation of Liberty County, Florida with notes on Fossil Diagenesis, Taphonomy, and preservation
Joel, Serena, University of South Florida Geology Department, Tampa, FL 33620
ABSTRACT- lithified rock samples containing Molluscan fauna were taken from the Pliocene age Jackson Bluff Formation located at the Alum Bluff in Liberty County Florida. The samples were brought back to the lab for interpretation and analysis. These samples contained mostly molds of taxa that were previously dissolved away by dissolution. Also, the samples were carefully separated and glued after all the salvageable taxa were isolated and identified with genus and species names. Counts of these …show more content…
abundances were noted and entered into Past to obtain a graph showing a diversity curve for that particular fossil assemblage. Dominance and evenness was noted, as well as, a graph and explanation shown in the figures and tables. A taxonomic composition pie chart was made to show the taxonomic percentages and compositions of the taxa obtained from the taxa in the fossil assemblage. A Faunal list of the taxa, overall total individual specimens, total abundance of each genus, and abundance of decayed, partially decayed, and non-decayed specimens in the fossil assemblage was also shown in the form of a table.
INTRODUCTION- Alum Bluff is one of the best natural geological exposures in the state of Florida, (Schmidt, 1986), (Figure 1). This locality was rather surprising in that exposures of different stratigraphic sections of a time span of thousands, if not millions of years was clearly visible in one specific area. The middle to late Tertiary deposits of the Florida panhandle has been known since the late 1800s, (Schmidt, 1986). They also have been described on numerous occasions, and have received the most attention from paleontologists attracted by their well-preserved mollusk assemblages (predominately neogene), (Schmidt, 1986). The Apalachicola River meanders 167 miles, it starts in the northeastern part of Georgia and goes all the way down to the northwestern part of the panhandle of Florida. Alum Bluff is located two miles north-northwest of Bristol, in Liberty County, Florida (Schmidt, 1986). The river cuts into the banks there exposing lots of molluscan fossils, eventually dumping its waters into the Gulf of Mexico. The Alum Bluff also exposes four main stratigraphic formations, oldest to youngest are the Chipola, Alum Bluff Group Undifferentiated, Jackson Bluff, and the Citronelle, (Figure 2).
Scientists are eager and what to know how these formations occurred, why they’re so diverse, what the underlying reasons were, and what caused them. This report stays within the realm of Jackson Bluff Formation and hypothesizes several key statements about the diversity, taxonomic composition, dominance, evenness, taphonomy, preservation, transportation, and fossil diagensis of this particular fossil assemblage. It specifically examines the taxonomic composition and diversity of the lithified samples and shows how their fossil diagensis, taphonomy, and preservational mode influenced it. The hypotheses here are crucial in understanding more about the paleo-community of the fossil assemblage found at this particular locality in the Jackson Bluff formation. If the hypotheses are correct, they will provide more knowledge about the diversity and taxonomic composition of the Alum Bluff.
A diversity analysis of the fauna found in those samples was performed because it tells us more about the overall molluscan assemblage found in the Jackson Bluff Formation exposed at Alum Bluff and provides knowledge about the richness, abundance, dominance and evenness of those taxa. The Fossil diagenesis, taphonomy, and preservational mode of the assemblage are important to note because this type of information tells us about what happened to these organisms after they died and possible biases in the fossil record. Their preservation mode tells us about the sediment in which these organisms were deposited in and provide clues to what exactly was in the water during their deposition, ph levels, and possibly even how long it took to deposit them, weather a rapid or slow burial process.
This study hypothesizes the following: 1) the fossils show evidence of transport. 2) Fossil diagensis, preservational mode, and taphonomy influenced taxonomic composition and diversity 3) a rarefaction diversity curve of the samples adequately characterizes the original diversity of the sampled horizon in the Jackson bluff formation. 4) The paleo-community was mostly dominated by a single species. This kind of paleontological scientific research can further our understanding of the Pliocene Jackson Bluff Formation at liberty county Florida. Also, if these four statements are true, our results will show data that supports them.
MATERIALS AND METHODS- Lithified rock samples were collected from the Jackson Bluff Formation exposed at N 30 28’ 13’’, W 84 59’ 9’’, the second locality visited at the Alum Bluff on February 2nd 2013. This locality was visited to do a stratigraphic section of the Alum Bluff; however, while doing a strat-column the samples were collected in a slumped outcrop of the Jackson Bluff Formation. The samples contained a diverse molluscan fauna preserved as molds and casts. A small fraction of the taxa in the samples contained there original calcite shell material. A diversity analysis of the molluscan faunal assemblage was performed as well as a brief examination of their taphonomy, fossil diagensis, and preservational mode. The samples were sealed with aluminum foil then placed in a ziplock bag. After, they were brought back from Alum bluff, processed in the lab, and carefully prepared. This was done to get a glimpse of the lithified layers showing all the taxa as well as their molds and casts. In doing this procedure, all the molluscan faunal diversity became clearly visible and allows one to see how these animals were persevered. This also allows one to take note of their fossil diagenesis, taphonomy and preservation. The layers held the lithified fauna together so separating; gluing, exposing the diversity of the assemblage, molds, casts, and unaltered shell material, and isolating intact specimens took time.
Every single shell that was not completely dissolved away by chemical dissolution was also isolated from the sample and identified to their genus and in some cases their species. After all of the taxa were isolated and identified, their abundances were counted and the data was entered into a program called PAST to get a rarefaction diversity curve of fossil the assemblage, (Hammer etal. 2005). Also, for the bivalves, counts were taken to distinguish all of the right, left, articulated, and indeterminate valves of each genus and all the individuals in each of those genera. The indeterminate valves were divided by two and added to the combination of the maximum number of right or left valves and the articulated valves. This gave an accurate estimate of the number of bivalves in the sampled fossil assemblage.
RESULTS- The rarefaction diversity curve in Figure 3 shows that the curve is passed its inflection point and leveling off at about 10 species but overall still increasing. In Table 1 there is a chart that shows a list of the fauna found in the fossil assemblage collected from the second locality visited along the Alum Bluff. In addition, this table shows the total number of individuals identified to genus and species, three preservation modes that the taxa were observed to be in upon discovery and the total number of abundances found in each of those three criteria. Visuals of the three preservation phases are shown with a scale for size, Figure 5. There were a total of 217 identified specimens in the sample, 11 non-dissolved calcite shell specimens, 47 partially dissolved calcite shell specimens, and 159 completely dissolved calcite shells, which left a mold as the only evidence of them being there, Figure 4.
Dominance and evenness are measures of the distribution of species abundances within a single community.
Looking at the data from PAST, it is clearly evident that the paleo-community of the fossil assemblage was fairly dominated by the single Mulinia indet., species with a dominance number of 0.455. The closer this number was to one, the more dominated the community was, (Hammer etal. 2005). Also, when looking at the evenness data from PAST a number of 0.343 was shown, indicating that the community was more dominated than even because the closer this number was to one the more even the community was. The pie chart in Figure 4 shows the taxonomic composition of the fossil assemblage. This is important because it shows percentages of the individuals found in the entire assemblage and shows how much of what genus and species dominated the paleo-community. 65.0% of the fossil assemblage community was dominated by Mulinia indet., Figure 4. The only species that came close to that was Nucluana indet. with …show more content…
11.0%.
DISCUSSION- By doing a rare faction diversity analysis, The graph shows that the curve has not reached an asymptote and is still rising indicating that if more samples were taken at that locality along the alum bluff, a chance of discovering more taxa seems plausible, Figure 3. Since the graph in Figure 3 looks as if it is still rising, and there is also a significant chance of discovering more taxa, the samples that were taken were not enough and therefore do not adequately characterizes the original diversity of the sampled horizon in the Jackson bluff formation. This means that hypothesis number three can be thrown out due to the lack of sampling size and effort. By using the Dominance/ evenness feature of PAST, coupled with the taxonomic compositional pie chart, the data shows that Mulinia indet., dominated the paleo-community in fossil assemblage with a taxanomic composition of 65%, shown in Figure 4. Therefore, hypothesis number four holds true and the data in the results section clearly support it. By observing the taphonomic composition of the fossil assemblage, it seems as if there is evidence of transportation of the fossils due to the amount of broken shell fragments that are cracked, crushed, disoriented, and found lithified together in the rock samples, Figure 6. Therefore, there is enough data here to support hypothesis number one suggesting that the fossils do show evidence of transportation after their original death and burial. However, the actual distance of transportation seems minimal, but is not known, and is out of the scope of the paper. 73.27% of the taxa in the entire fossil assemblage were dissolved specimens and it is thought that these taxa were buried slowly which would have allowed chemical dissolution to take place in an environment where Ph was rather high. In addition, when looking at the transitional phase of fossil diagenesis and preservational mode number three, the taxa in that critera has such a high dissolution percentage, supporting the idea that the uppermost part of the Jackson Bluff formation consist primarily of molds of completely dissolved mollusks.
It was noted in phase one that the taxa were white and that there was no evidence of chemical dissolution. This phase consisted of about 5.07% of the taxa in the fossil assemblage and is possibly indicative of a fairly quick burial and lagoon type depositional environment in the uppermost Jackson Bluff, Table 1. The paleo-environment in this area could have been such that it maintained a fairly normal Ph balance keeping the fossils preserved from dissolving agents such as chemicals in the water that would increase Ph, Figure 5. Phase two, was an intermediate phase between the two and the taxa were brown looking but the calcite shell material was not completely dissolved away, Figure 5. This preservation phase consisted of approximately 21.66% of the entire fossil assemblage, Table 1. Phase three was the most abundant phase of the assemblage and the taxa in this phase was completely dissolved away; an impression or mold of the lithified rock remained held together supporting the idea that the uppermost Jackson Bluff Formation consists primarily of molds, Figure 5. This preservation phase consisted of approximately 73.27% of the entire fossil assemblage, Table 1.
Although our rarefaction curve tells us that more taxa is yet to be found at this locality, these diagenetic, taphonomic, and preservation modal processes influenced taxonomic composition and played a role in biasing the diversity in a manner of transportation, disorientation, and chemical dissolution of the molluscan taxa. This was due to the evidence of broken shell fragments, as well as the amount of completely dissolved shells that left there impression in the lithified rock samples. Therefore the data here support hypothesis number two in that Fossil diagensis, preservational mode, and taphonomy have influenced taxonomic composition and diversity of the fossil assemblage. All in all, the data shown in this report either supports or doesn’t supports the hypotheses proposed and provides more background knowledge about the divesity, taphonomy, preservation and fossil diagenesis of the taxa found in this fossil assemblage at the second locality visited along the Alum Bluff. Overall, these results have improved our understanding of the Pliocene molluscan fauna in the Jackson Bluff Formation exposed along the Alum Bluff at this locality. In the future, this project can be taken further by sampling more of that particular locality to find out how much more taxa is actually there in attempts to adequately characterizes the original diversity of the sampled locality. Also, possibly even sampling different areas of the uppermost Jackson Bluff both stratigraphically and spatially and comparing the sample level diversity to see how it changes through time and space.
TABLES AND FIGURES
Table 1- Faunal list of the taxa, overall total individual specimens, total abundances of each genus, abundance of decayed, partially decayed, and non-decayed specimens, and percent of dissolved/non-dissolved taxa found in the fossil assemblage Faunal List | Total Abundance for each taxa | 1) Abundance of non-dissolved calcite shells | 2) Abundance of partially dissolved calcite Shells | 3) Abundance of completely dissolved calcite shells | Thracia phaseolina | 1 | 0 | 1 | 0 | Lucinoma filosa | 1 | 1 | 0 | 0 | Nuculana Jamaicensis | 2 | 2 | 0 | 0 | Toritella segmenta | 2 | 0 | 1 | 1 | Gastreopoda indet.
| 2 | 0 | 0 | 2 | Thracia indet. | 10 | 0 | 3 | 7 | Dentalium indet. | 14 | 1 | 3 | 10 | Cadulus indet. | 19 | 2 | 3 | 14 | Nucluana indet. | 24 | 0 | 8 | 16 | Mulinia indet. | 142 | 5 | 28 | 109 | TOTAL ABUNDANCES | 217 | 11 | 47 | 159 | | Percent of dissolved/ non-dissolved taxa | 5.07% | 21.66% | 73.27% |
Figure1, Map Showing location of The Alum Bluff Formation (Noles, 2009)
Figure 2, Geologic stratigraphic section of Alum Bluff (Jarzen et al. 2010). The fossil assemblage was found in the stratigraphic section where the arrow is pointing. In that location, there are lots of Argillaceous sand, and many molds of
mollusks.
Figure 3, Rarefaction diversity curve of the fossil assemblage
Figure 4, pie chart showing the taxonomic composition the fossil assemblage
1 inch = 1 cm
1 inch = 1 cm
Phase 3
Phase 3
Phase 2
Phase 2
Phase 1
Phase 1
Figure 5, Visuals of the three preservation/transitional phases
1 inch= 1.5 cm cm
1 inch= 1.5 cm cm
Figure 6- Visual showing a partially broken, decayed mulinia specimen and other shell fragments
ACKNOWLEDGEMENTS- I wish to thank Joshua Slattery for the many hours of discussion about this topic, and the valuable advice he shared with me throughout the progress of this project. He influenced, challenged, encouraged, and helped me dig deeper into the subject matter and got me started on this project from the day the fossils were found. Also, special thanks go out to my paleontology professor, Brian Andres, ph.D. Also, I would like to thank my friend Karisa kroslack for the pictures that she took for me with her camera.
REFERENCES
`Hammer, Harper, 2005. paleontological data analysis, Blackwell.
Jarzen et al. 2010, Palynology and paleoecology of the middle Miocene Alum Bluff Flora, Liberty County, Florida, USA. Geoscience World, AASP Foundation, Palynology December 2010, V. 34. No. 2, p. 261-268
Noles, 20 December 2009, Wikimedia Commons, Alum Bluff Group. Png, Page 1.
Schmidt, W. 1986. Alum, Bluff, Liberty County, Florida. Geological Society of America Centennial Field Guider Southern Section, Page 355-357.
Joel, Serena, University of South Florida Geology Department, Tampa, FL 33620
ABSTRACT- lithified rock samples containing Molluscan fauna were taken from the Pliocene age Jackson Bluff Formation located at the Alum Bluff in Liberty County Florida. The samples were brought back to the lab for interpretation and analysis. These samples contained mostly molds of taxa that were previously dissolved away by dissolution. Also, the samples were carefully separated and glued after all the salvageable taxa were isolated and identified with genus and species names. Counts of these …show more content…
abundances were noted and entered into Past to obtain a graph showing a diversity curve for that particular fossil assemblage. Dominance and evenness was noted, as well as, a graph and explanation shown in the figures and tables. A taxonomic composition pie chart was made to show the taxonomic percentages and compositions of the taxa obtained from the taxa in the fossil assemblage. A Faunal list of the taxa, overall total individual specimens, total abundance of each genus, and abundance of decayed, partially decayed, and non-decayed specimens in the fossil assemblage was also shown in the form of a table.
INTRODUCTION- Alum Bluff is one of the best natural geological exposures in the state of Florida, (Schmidt, 1986), (Figure 1). This locality was rather surprising in that exposures of different stratigraphic sections of a time span of thousands, if not millions of years was clearly visible in one specific area. The middle to late Tertiary deposits of the Florida panhandle has been known since the late 1800s, (Schmidt, 1986). They also have been described on numerous occasions, and have received the most attention from paleontologists attracted by their well-preserved mollusk assemblages (predominately neogene), (Schmidt, 1986). The Apalachicola River meanders 167 miles, it starts in the northeastern part of Georgia and goes all the way down to the northwestern part of the panhandle of Florida. Alum Bluff is located two miles north-northwest of Bristol, in Liberty County, Florida (Schmidt, 1986). The river cuts into the banks there exposing lots of molluscan fossils, eventually dumping its waters into the Gulf of Mexico. The Alum Bluff also exposes four main stratigraphic formations, oldest to youngest are the Chipola, Alum Bluff Group Undifferentiated, Jackson Bluff, and the Citronelle, (Figure 2).
Scientists are eager and what to know how these formations occurred, why they’re so diverse, what the underlying reasons were, and what caused them. This report stays within the realm of Jackson Bluff Formation and hypothesizes several key statements about the diversity, taxonomic composition, dominance, evenness, taphonomy, preservation, transportation, and fossil diagensis of this particular fossil assemblage. It specifically examines the taxonomic composition and diversity of the lithified samples and shows how their fossil diagensis, taphonomy, and preservational mode influenced it. The hypotheses here are crucial in understanding more about the paleo-community of the fossil assemblage found at this particular locality in the Jackson Bluff formation. If the hypotheses are correct, they will provide more knowledge about the diversity and taxonomic composition of the Alum Bluff.
A diversity analysis of the fauna found in those samples was performed because it tells us more about the overall molluscan assemblage found in the Jackson Bluff Formation exposed at Alum Bluff and provides knowledge about the richness, abundance, dominance and evenness of those taxa. The Fossil diagenesis, taphonomy, and preservational mode of the assemblage are important to note because this type of information tells us about what happened to these organisms after they died and possible biases in the fossil record. Their preservation mode tells us about the sediment in which these organisms were deposited in and provide clues to what exactly was in the water during their deposition, ph levels, and possibly even how long it took to deposit them, weather a rapid or slow burial process.
This study hypothesizes the following: 1) the fossils show evidence of transport. 2) Fossil diagensis, preservational mode, and taphonomy influenced taxonomic composition and diversity 3) a rarefaction diversity curve of the samples adequately characterizes the original diversity of the sampled horizon in the Jackson bluff formation. 4) The paleo-community was mostly dominated by a single species. This kind of paleontological scientific research can further our understanding of the Pliocene Jackson Bluff Formation at liberty county Florida. Also, if these four statements are true, our results will show data that supports them.
MATERIALS AND METHODS- Lithified rock samples were collected from the Jackson Bluff Formation exposed at N 30 28’ 13’’, W 84 59’ 9’’, the second locality visited at the Alum Bluff on February 2nd 2013. This locality was visited to do a stratigraphic section of the Alum Bluff; however, while doing a strat-column the samples were collected in a slumped outcrop of the Jackson Bluff Formation. The samples contained a diverse molluscan fauna preserved as molds and casts. A small fraction of the taxa in the samples contained there original calcite shell material. A diversity analysis of the molluscan faunal assemblage was performed as well as a brief examination of their taphonomy, fossil diagensis, and preservational mode. The samples were sealed with aluminum foil then placed in a ziplock bag. After, they were brought back from Alum bluff, processed in the lab, and carefully prepared. This was done to get a glimpse of the lithified layers showing all the taxa as well as their molds and casts. In doing this procedure, all the molluscan faunal diversity became clearly visible and allows one to see how these animals were persevered. This also allows one to take note of their fossil diagenesis, taphonomy and preservation. The layers held the lithified fauna together so separating; gluing, exposing the diversity of the assemblage, molds, casts, and unaltered shell material, and isolating intact specimens took time.
Every single shell that was not completely dissolved away by chemical dissolution was also isolated from the sample and identified to their genus and in some cases their species. After all of the taxa were isolated and identified, their abundances were counted and the data was entered into a program called PAST to get a rarefaction diversity curve of fossil the assemblage, (Hammer etal. 2005). Also, for the bivalves, counts were taken to distinguish all of the right, left, articulated, and indeterminate valves of each genus and all the individuals in each of those genera. The indeterminate valves were divided by two and added to the combination of the maximum number of right or left valves and the articulated valves. This gave an accurate estimate of the number of bivalves in the sampled fossil assemblage.
RESULTS- The rarefaction diversity curve in Figure 3 shows that the curve is passed its inflection point and leveling off at about 10 species but overall still increasing. In Table 1 there is a chart that shows a list of the fauna found in the fossil assemblage collected from the second locality visited along the Alum Bluff. In addition, this table shows the total number of individuals identified to genus and species, three preservation modes that the taxa were observed to be in upon discovery and the total number of abundances found in each of those three criteria. Visuals of the three preservation phases are shown with a scale for size, Figure 5. There were a total of 217 identified specimens in the sample, 11 non-dissolved calcite shell specimens, 47 partially dissolved calcite shell specimens, and 159 completely dissolved calcite shells, which left a mold as the only evidence of them being there, Figure 4.
Dominance and evenness are measures of the distribution of species abundances within a single community.
Looking at the data from PAST, it is clearly evident that the paleo-community of the fossil assemblage was fairly dominated by the single Mulinia indet., species with a dominance number of 0.455. The closer this number was to one, the more dominated the community was, (Hammer etal. 2005). Also, when looking at the evenness data from PAST a number of 0.343 was shown, indicating that the community was more dominated than even because the closer this number was to one the more even the community was. The pie chart in Figure 4 shows the taxonomic composition of the fossil assemblage. This is important because it shows percentages of the individuals found in the entire assemblage and shows how much of what genus and species dominated the paleo-community. 65.0% of the fossil assemblage community was dominated by Mulinia indet., Figure 4. The only species that came close to that was Nucluana indet. with …show more content…
11.0%.
DISCUSSION- By doing a rare faction diversity analysis, The graph shows that the curve has not reached an asymptote and is still rising indicating that if more samples were taken at that locality along the alum bluff, a chance of discovering more taxa seems plausible, Figure 3. Since the graph in Figure 3 looks as if it is still rising, and there is also a significant chance of discovering more taxa, the samples that were taken were not enough and therefore do not adequately characterizes the original diversity of the sampled horizon in the Jackson bluff formation. This means that hypothesis number three can be thrown out due to the lack of sampling size and effort. By using the Dominance/ evenness feature of PAST, coupled with the taxonomic compositional pie chart, the data shows that Mulinia indet., dominated the paleo-community in fossil assemblage with a taxanomic composition of 65%, shown in Figure 4. Therefore, hypothesis number four holds true and the data in the results section clearly support it. By observing the taphonomic composition of the fossil assemblage, it seems as if there is evidence of transportation of the fossils due to the amount of broken shell fragments that are cracked, crushed, disoriented, and found lithified together in the rock samples, Figure 6. Therefore, there is enough data here to support hypothesis number one suggesting that the fossils do show evidence of transportation after their original death and burial. However, the actual distance of transportation seems minimal, but is not known, and is out of the scope of the paper. 73.27% of the taxa in the entire fossil assemblage were dissolved specimens and it is thought that these taxa were buried slowly which would have allowed chemical dissolution to take place in an environment where Ph was rather high. In addition, when looking at the transitional phase of fossil diagenesis and preservational mode number three, the taxa in that critera has such a high dissolution percentage, supporting the idea that the uppermost part of the Jackson Bluff formation consist primarily of molds of completely dissolved mollusks.
It was noted in phase one that the taxa were white and that there was no evidence of chemical dissolution. This phase consisted of about 5.07% of the taxa in the fossil assemblage and is possibly indicative of a fairly quick burial and lagoon type depositional environment in the uppermost Jackson Bluff, Table 1. The paleo-environment in this area could have been such that it maintained a fairly normal Ph balance keeping the fossils preserved from dissolving agents such as chemicals in the water that would increase Ph, Figure 5. Phase two, was an intermediate phase between the two and the taxa were brown looking but the calcite shell material was not completely dissolved away, Figure 5. This preservation phase consisted of approximately 21.66% of the entire fossil assemblage, Table 1. Phase three was the most abundant phase of the assemblage and the taxa in this phase was completely dissolved away; an impression or mold of the lithified rock remained held together supporting the idea that the uppermost Jackson Bluff Formation consists primarily of molds, Figure 5. This preservation phase consisted of approximately 73.27% of the entire fossil assemblage, Table 1.
Although our rarefaction curve tells us that more taxa is yet to be found at this locality, these diagenetic, taphonomic, and preservation modal processes influenced taxonomic composition and played a role in biasing the diversity in a manner of transportation, disorientation, and chemical dissolution of the molluscan taxa. This was due to the evidence of broken shell fragments, as well as the amount of completely dissolved shells that left there impression in the lithified rock samples. Therefore the data here support hypothesis number two in that Fossil diagensis, preservational mode, and taphonomy have influenced taxonomic composition and diversity of the fossil assemblage. All in all, the data shown in this report either supports or doesn’t supports the hypotheses proposed and provides more background knowledge about the divesity, taphonomy, preservation and fossil diagenesis of the taxa found in this fossil assemblage at the second locality visited along the Alum Bluff. Overall, these results have improved our understanding of the Pliocene molluscan fauna in the Jackson Bluff Formation exposed along the Alum Bluff at this locality. In the future, this project can be taken further by sampling more of that particular locality to find out how much more taxa is actually there in attempts to adequately characterizes the original diversity of the sampled locality. Also, possibly even sampling different areas of the uppermost Jackson Bluff both stratigraphically and spatially and comparing the sample level diversity to see how it changes through time and space.
TABLES AND FIGURES
Table 1- Faunal list of the taxa, overall total individual specimens, total abundances of each genus, abundance of decayed, partially decayed, and non-decayed specimens, and percent of dissolved/non-dissolved taxa found in the fossil assemblage Faunal List | Total Abundance for each taxa | 1) Abundance of non-dissolved calcite shells | 2) Abundance of partially dissolved calcite Shells | 3) Abundance of completely dissolved calcite shells | Thracia phaseolina | 1 | 0 | 1 | 0 | Lucinoma filosa | 1 | 1 | 0 | 0 | Nuculana Jamaicensis | 2 | 2 | 0 | 0 | Toritella segmenta | 2 | 0 | 1 | 1 | Gastreopoda indet.
| 2 | 0 | 0 | 2 | Thracia indet. | 10 | 0 | 3 | 7 | Dentalium indet. | 14 | 1 | 3 | 10 | Cadulus indet. | 19 | 2 | 3 | 14 | Nucluana indet. | 24 | 0 | 8 | 16 | Mulinia indet. | 142 | 5 | 28 | 109 | TOTAL ABUNDANCES | 217 | 11 | 47 | 159 | | Percent of dissolved/ non-dissolved taxa | 5.07% | 21.66% | 73.27% |
Figure1, Map Showing location of The Alum Bluff Formation (Noles, 2009)
Figure 2, Geologic stratigraphic section of Alum Bluff (Jarzen et al. 2010). The fossil assemblage was found in the stratigraphic section where the arrow is pointing. In that location, there are lots of Argillaceous sand, and many molds of
mollusks.
Figure 3, Rarefaction diversity curve of the fossil assemblage
Figure 4, pie chart showing the taxonomic composition the fossil assemblage
1 inch = 1 cm
1 inch = 1 cm
Phase 3
Phase 3
Phase 2
Phase 2
Phase 1
Phase 1
Figure 5, Visuals of the three preservation/transitional phases
1 inch= 1.5 cm cm
1 inch= 1.5 cm cm
Figure 6- Visual showing a partially broken, decayed mulinia specimen and other shell fragments
ACKNOWLEDGEMENTS- I wish to thank Joshua Slattery for the many hours of discussion about this topic, and the valuable advice he shared with me throughout the progress of this project. He influenced, challenged, encouraged, and helped me dig deeper into the subject matter and got me started on this project from the day the fossils were found. Also, special thanks go out to my paleontology professor, Brian Andres, ph.D. Also, I would like to thank my friend Karisa kroslack for the pictures that she took for me with her camera.
REFERENCES
`Hammer, Harper, 2005. paleontological data analysis, Blackwell.
Jarzen et al. 2010, Palynology and paleoecology of the middle Miocene Alum Bluff Flora, Liberty County, Florida, USA. Geoscience World, AASP Foundation, Palynology December 2010, V. 34. No. 2, p. 261-268
Noles, 20 December 2009, Wikimedia Commons, Alum Bluff Group. Png, Page 1.
Schmidt, W. 1986. Alum, Bluff, Liberty County, Florida. Geological Society of America Centennial Field Guider Southern Section, Page 355-357.