Were bivalves ecologically dominant over brachiopods in the late Paleozoic? A test using exceptionally preserved fossil assemblages

Paleobiology ◽  
2019 ◽  
Vol 45 (02) ◽  
pp. 265-279 ◽  
Author(s):  
Shannon Hsieh ◽  
Andrew M. Bush ◽  
J Bret Bennington
Keyword(s):  
Fossil Record ◽  
Energy Use ◽  
Regional Scale ◽  
Late Paleozoic ◽  
Ecosystem Structure ◽  
Relative Importance ◽  
Clear Trend ◽  
Fossil Assemblages ◽  
Ecological Importance ◽  
Preferential Dissolution

AbstractInterpreting changes in ecosystem structure from the fossil record can be challenging. In a prominent example, the traditional view that brachiopods were ecologically dominant over bivalves in the Paleozoic has been disputed on both taphonomic and metabolic grounds. Aragonitic bivalves may be underrepresented in many fossil assemblages due to preferential dissolution. Abundance counts may further understate the ecological importance of bivalves, which tend to have more biomass and higher metabolic rates than brachiopods. We evaluate the relative importance of the two clades in exceptionally preserved, bulk-sampled fossil assemblages from the Pennsylvanian Breathitt Formation of Kentucky, where aragonitic bivalves are preserved as shells, not molds. At the regional scale, brachiopods were twice as abundant as bivalves and were collectively equivalent in biomass and energy use. Analyses of samples from the Paleobiology Database that contain abundance counts are consistent with these results and show no clear trend in the relative ecological importance of bivalves during the middle and late Paleozoic. Bivalves were probably more important in Paleozoic ecosystems than is apparent in many fossil assemblages, but they were not clearly dominant over brachiopods until after the Permian–Triassic extinction, which caused the shelly benthos to shift from bivalve and brachiopod dominated to merely bivalve dominated.

scholarly journals The effects of geographic range size and abundance on extinction during a time of “sluggish”’ evolution

Paleobiology ◽  
2020 ◽  
pp. 1-14
Author(s):  
Michelle M. Casey ◽  
Erin E. Saupe ◽  
Bruce S. Lieberman
Keyword(s):  
North American ◽  
Fossil Record ◽  
Extinction Risk ◽  
Geographic Range ◽  
Range Size ◽  
Late Paleozoic ◽  
The North ◽  
Geographic Range Size ◽  
The Relationship ◽  
Habitat Tracking

Abstract Geographic range size and abundance are important determinants of extinction risk in fossil and extant taxa. However, the relationship between these variables and extinction risk has not been tested extensively during evolutionarily “quiescent” times of low extinction and speciation in the fossil record. Here we examine the influence of geographic range size and abundance on extinction risk during the late Paleozoic (Mississippian–Permian), a time of “sluggish” evolution when global rates of origination and extinction were roughly half those of other Paleozoic intervals. Analyses used spatiotemporal occurrences for 164 brachiopod species from the North American midcontinent. We found abundance to be a better predictor of extinction risk than measures of geographic range size. Moreover, species exhibited reductions in abundance before their extinction but did not display contractions in geographic range size. The weak relationship between geographic range size and extinction in this time and place may reflect the relative preponderance of larger-ranged taxa combined with the physiographic conditions of the region that allowed for easy habitat tracking that dampened both extinction and speciation. These conditions led to a prolonged period (19–25 Myr) during which standard macroevolutionary rules did not apply.

Maritime built heritage and marine wildlife: Remote sensing as a tool to identify and prioritise integrated conservation in coastal environments

2021 ◽  
Author(s):  
Tim Baxter ◽  
Martin Coombes ◽  
Heather Viles
Keyword(s):  
Remote Sensing ◽  
Structural Information ◽  
Regional Scale ◽  
Initial Assessment ◽  
Marine Biodiversity ◽  
Engineering Structures ◽  
Built Heritage ◽  
Ecological Importance ◽  
Integrated Conservation ◽  
Marine Wildlife

<p>Maritime built heritage is threatened by natural hazards and human activities around the world. Likewise, marine wildlife is increasingly threatened by the effects of climate change and human development. Due to their age and traditional construction, maritime built heritage (e.g. historic harbours) may provide unique habitats for diverse assemblages of marine wildlife. Yet, as aspects of built heritage are often missing in assessments of marine infrastructure, identifying which heritage assets have the potential to provide the greatest ecological benefits remains a challenge. An improved understanding of the ecological importance of maritime built heritage can enhance arguments for its continued protection, maintenance and repair. At the same time, this may present new opportunities to conserve important and largely unidentified hotspots of marine biodiversity.</p><p>Using preliminary results from the Isles of Scilly, UK, this study presents a novel method for quantifying the full extent of marine engineering structures (including heritage assets) at a regional scale, and for identifying priority structures for joint biodiversity and heritage conservation.</p><p>Remote sensing data were considered alongside historic environment data and records of modern coastal defences in a rapid desk-based assessment to create a complete inventory of marine structures along the entire coastline of the Isles of Scilly. In total, 68 structures were recorded (6,180 m in length), with over half registered as heritage assets. LiDAR and aerial photography were used to determine the site characteristics of each structure (e.g. shore position). This allowed for an initial assessment of the potential ecological importance of these structures when considered alongside structural information, including building age and material. By evaluating the ecological potential and heritage value of each structure using a novel scoring system, priorities for conservation and other managed interventions are identified. This includes listed buildings and scheduled monuments that due to their construction features and shore position are most likely to support diverse marine assemblages.</p><p>Combined ecological-heritage evaluations incorporating remote sensing datasets allow for the identification of those structures with the greatest potential for the integrated conservation of built heritage and marine wildlife. Research is now needed to develop this method further, ground-truth its outputs, and test its application in other geographical locations and at varying scales.</p>

scholarly journals Shifts in the relative fitness contributions of fecundity and survival in variable and changing environments

2021 ◽  
Vol 224 (Suppl 1) ◽  
pp. jeb228031
Author(s):  
Lauren B. Buckley ◽  
Sean D. Schoville ◽  
Caroline M. Williams
Keyword(s):  
Environmental Conditions ◽  
Energy Use ◽  
Environmental Gradients ◽  
Relative Fitness ◽  
Relative Importance ◽  
Fitness Components ◽  
Climate Variability And Change ◽  
Short Term ◽  
Climate Gradients ◽  
Recent Climate

ABSTRACTOrganisms respond to shifts in climate means and variability via distinct mechanisms. Accounting for these differential responses and appropriately aggregating them is central to understanding and predicting responses to climate variability and change. Separately considering fitness components can clarify organismal responses: fecundity is primarily an integrated, additive response to chronic environmental conditions over time via mechanisms such as energy use and acquisition, whereas survival can be strongly influenced by short-term, extreme environmental conditions. In many systems, the relative importance of fecundity and survival constraints changes systematically along climate gradients, with fecundity constraints dominating at high latitudes or altitudes (i.e. leading range edges as climate warms), and survival constraints dominating at trailing range edges. Incorporating these systematic differences in models may improve predictions of responses to recent climate change over models that assume similar processes along environmental gradients. We explore how detecting and predicting shifts in fitness constraints can improve our ability to forecast responses to climate gradients and change.

Coral microatolls and a probable Middle Ordovician example

1990 ◽  
Vol 64 (1) ◽  
pp. 39-43 ◽  
Author(s):  
David R. Kobluk ◽  
Iqbal Noor
Keyword(s):  
Coral Reefs ◽  
Fossil Record ◽  
Scleractinian Coral ◽  
Regional Scale ◽  
Southern Ontario ◽  
Middle Ordovician ◽  
Reef Environments ◽  
Maximum Water ◽  
Water Depths ◽  
Tabulate Corals

A disk-shaped massive colony of Tetradium, from the Middle Ordovician Bobcaygeon Formation in southern Ontario, displays features of a coral microatoll. This is the first pre-Holocene coral microatoll yet described, indicating that some tabulate corals in level-bottom communities were growing as microatolls as do many modern colonial skeleton-secreting organisms.The microatoll therefore is not strictly a Quaternary or even Cenozoic phenomenon, but has a fossil record that may span most of the Phanerozoic. This indicates that the special conditions necessary for microatoll growth have existed outside of reef environments, and were present before the advent of scleractinian coral reefs. It may be possible to use ancient microatolls to estimate absolute water depths at low tide, thereby providing a means for estimating maximum water depths on a local and regional scale.

scholarly journals Unusually variable paleocommunity composition in the oldest metazoan fossil assemblages

Paleobiology ◽  
2019 ◽  
Vol 45 (02) ◽  
pp. 235-245 ◽  
Author(s):  
Seth Finnegan ◽  
James G. Gehling ◽  
Mary L. Droser
Keyword(s):  
Fossil Record ◽  
Benthic Communities ◽  
Benthic Assemblages ◽  
Β Diversity ◽  
Marine Habitats ◽  
Fossil Assemblages ◽  
Early Metazoan ◽  
Insight Into ◽  
Faunal Variability ◽  
Ecological Differences

AbstractRecent excavations of Ediacaran assemblages have revealed striking bed-to-bed variation in diversity–abundance structure, offering potential insight into the ecology and taphonomy of these poorly understood early Metazoan ecosystems. Here we compare faunal variability in Ediacaran assemblages to that of younger benthic assemblages, both fossil and modern. We decompose the diversity of local assemblages into within-collection (α) and among-collection (β) components and show that β diversity in Ediacaran assemblages is unusually high relative to younger assemblages. Average between-bed ecological dissimilarities in the Phanerozoic fossil record are comparable to within-habitat dissimilarities typically observed over meter to kilometer scales in modern benthic marine habitats, but dissimilarities in Ediacaran assemblages are comparable to those typically observed over 10–100 km scales in modern habitats. We suggest that the unusually variable diversity–abundance structure of Ediacaran assemblages is due both to their preservation as near snapshots of benthic communities and to original ecological differences, in particular the paucity of motile taxa and the near lack of predation and infaunalization.

Taphonomic approaches to time resolution in fossil assemblages: Introduction

1993 ◽  
Vol 6 ◽  
pp. 1-8 ◽  
Author(s):  
Susan M. Kidwell ◽  
Anna K. Behrensmeyer
Keyword(s):  
Time Resolution ◽  
Professional Education ◽  
Fossil Record ◽  
Taxonomic Group ◽  
Relative Time ◽  
Short Course ◽  
Paleontological Society ◽  
Historical Geology ◽  
Fossil Assemblages ◽  
Short Courses

Since their inception in 1978, the annual short courses sponsored by the Paleontological Society have aimed to broaden and to enhance the professional education of paleontologists, including students new to the field. The 1993 short course continues in that tradition, but differs from many previous courses in focussing not on a taxonomic group but on a broader aspect of the fossil record, namely the time resolution of fossil assemblages. This seemed an especially good topic for a short course because questions of absolute and relative time – how old? how fast? how synchronously? – pervade paleontology and historical geology in general.

Modeled physiological mechanisms for observed changes in the late Paleozoic plant fossil record

2021 ◽  
Vol 562 ◽  
pp. 110056
Author(s):  
Jon D. Richey ◽  
Isabel P. Montañez ◽  
Joseph D. White ◽  
William A. DiMichele ◽  
William J. Matthaeus ◽  
...  
Keyword(s):  
Fossil Record ◽  
Late Paleozoic ◽  
Physiological Mechanisms ◽  
Plant Fossil

Preservation is predictable: quantifying the effect of taphonomic biases on ecological disparity in birds

Paleobiology ◽  
2015 ◽  
Vol 41 (2) ◽  
pp. 353-367 ◽  
Author(s):  
Jonathan S. Mitchell
Keyword(s):  
Sample Size ◽  
Environmental Conditions ◽  
Fossil Record ◽  
Large Scale ◽  
Morphological Disparity ◽  
Bird Assemblages ◽  
Lacustrine Deposits ◽  
Fossil Assemblages ◽  
Fossil Data ◽  
Relative Scarcity

AbstractEvolutionary inferences from fossil data often require accurately reconstructing differences in richness and morphological disparity between fossil sites across space and time. Biases such as sampling and rock availability are commonly accounted for in large-scale studies; however, preservation bias is usually dealt with only in smaller, more focused studies. Birds represent a diverse, but taphonomically fragile, group commonly used to infer environmental conditions in recent (Pleistocene and later) fossil assemblages, and their relative scarcity in the fossil record has led to controversy over the timing of their radiation. Here, I use simulations to show how even weak taphonomic biases can distort estimates of richness, and render variance sensitive to sample size. I then apply an ecology-based filtering model to recent bird assemblages to quantify the distortion induced by taphonomy. Certain deposit types, such as caves, show less evidence of taphonomic distortion than others, such as fluvial and lacustrine deposits. Archaeological middens unsurprisingly show some of the strongest evidence for taphonomic bias, and they should be avoided when reconstructing Pleistocene and early Holocene environments. Further, these results support previously suggested methods for detecting fossil assemblages that are relatively faithfully preserved (e.g., presence of difficult-to-preserve taxa), and I use these results to recommend that future large-scale studies include facies diversity along with metrics such as rock volume, or compare only sites with similar taphonomic histories.

Evidence of oribatid mite detritivory in Antarctica during the late Paleozoic and Mesozoic

2004 ◽  
Vol 78 (6) ◽  
pp. 1146-1153 ◽  
Author(s):  
Derek W. Kellogg ◽  
Edith L. Taylor
Keyword(s):  
Fossil Record ◽  
Oribatid Mite ◽  
Late Paleozoic ◽  
Transantarctic Mountains ◽  
Animal Interaction ◽  
Wood Boring

Despite their importance in breaking down lignified tissue today, much is still unknown about the role of mites in the fossil record, especially with reference to the Paleozoic–Mesozoic transition. This study examines permineralized peat from three localities in the central Transantarctic Mountains, ranging in age from Permian to Jurassic, for evidence of diversity and abundance of wood-boring mites. Evidence of mites, in the form of coprolites and tunnels in wood and other tissues, was found at all three localities; the Triassic site included more than 10 times as many wood borings as the Permian site. Our results supplement prior evidence of wood-boring mites during the Mesozoic and thereby fill in the known geologic range of this plant/animal interaction.

The morphology of the terminal phalanges in Permo-Carboniferous synapsids: an evolutionary perspective

2007 ◽  
Vol 44 (2) ◽  
pp. 267-274 ◽  
Author(s):  
Hillary C Maddin ◽  
Robert R Reisz
Keyword(s):  
Fossil Record ◽  
Feeding Behaviour ◽  
Shape Change ◽  
Morphological Features ◽  
Evolutionary Perspective ◽  
Crown Group ◽  
Clear Trend ◽  
Informative Signal ◽  
Size And Shape ◽  
And Function

Morphological features of the terminal phalanges of extinct tetrapods can be used to infer whether or not keratinous claws were present even though these structures are not preserved in the fossil record. Such features as dense vascularization grooves and foramina, and a general claw-like morphology, are present in some of the earliest fully terrestrial tetrapods, the Permo-Carboniferous synapsids. Early synapsids are represented by a rich fossil record that preserves the detailed anatomy of the terminal phalanges and allows for an examination of the early evolution of these structures in a well-resolved phylogenetic context. The pattern of change in the morphology of the terminal phalanges of five basal synapsids, Cotylorhynchus romeri, Varanops sp., Edaphosaurus boanerges, Haptodus garnettensis, and Dimetrodon limbatus, reveals a clear trend from a broad, flat, and spatulate morphology in the basal taxa to a tall, narrow, and curved structure. This trend in overall shape change does not reflect changes in feeding behaviour. The size and shape of the flexor tubercle appears to be a factor of size and function, rather than possessing a phylogenetically informative signal. The osteological features used to infer the presence of a keratinous sheath in the synapsids are also observed in the non-amniote taxon Diadectes absitus. This indicates that claws were not an amniote innovation and that they instead originated somewhere outside the crown group Amniota.

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