scholarly journals Exceptional preservation of comma shrimp from a mid-Cretaceous Lagerstätte of Colombia, and the origins of crown Cumacea

2019 ◽  
Vol 286 (1916) ◽  
pp. 20191863 ◽  
Author(s):  
Javier Luque ◽  
Sarah Gerken
Keyword(s):  
Fossil Record ◽  
Large Sample Size ◽  
High Latitudes ◽  
Benthic Organisms ◽  
Fine Grained ◽  
Exceptional Preservation ◽  
Phylogenetic Studies ◽  
Thoracic Legs ◽  
Fossil Records ◽  
Mass Accumulation

Mesozoic rocks with exceptional preservation of marine arthropods are known worldwide but largely restricted to mid–high latitudes. The scarcity of assemblages with exceptional preservation in low, tropical latitudes greatly limits our understanding of the origins of several modern groups and the evolution of tropical biotas through time. Here, we report the oldest crown Cumacea, or ‘comma’ shrimp (Arthropoda: Eumalacostraca: Peracarida) with modern familial affinities, from a new mid-Cretaceous (95–90 Ma) Lagerstätte in tropical South America. Cumaceans have one of the poorest fossil records among marine arthropods, despite today being abundant and speciose benthic organisms associated with fine-grained sediments with high fossilization potential. Eobodotria muisca gen. et sp. nov., found in mass accumulation surfaces, preserves with detail the gut, mouth parts, thoracic legs/pereopods, pleopods, uropods bearing setae, antennal flagella and even small eyes bearing ommatidia. These features, rarely preserved in fossil crustaceans, plus the large sample size (greater than 200 individuals, 6–8 mm long), allow us to discuss phylogenetic/systematic aspects and explore possible mechanisms behind their unusual accumulation. Eobodotria bridges an approximately 165 Myr gap in the cumacean fossil record, provides a reliable calibration point for phylogenetic studies and expands our understanding of exceptional preservation in past and present tropical settings.

scholarly journals Biogeographic and evolutionary patterns of change in the terrestrial biota across the Cretaceous\Tertiary boundary

1992 ◽  
Vol 6 ◽  
pp. 60-60
Author(s):  
William A. Clemens
Keyword(s):  
Late Cretaceous ◽  
Fossil Record ◽  
Taxonomic Diversity ◽  
High Latitudes ◽  
Apparent Paradox ◽  
Evolutionary Patterns ◽  
Geographic Ranges ◽  
Terrestrial Vertebrates ◽  
Terrestrial Biota ◽  
Fossil Records

The currently available fossil record suggests, 1) biogeographic differentiation of the Late Cretaceous terrestrial biota and, 2) distinctly different patterns of evolution of terrestrial faunas and floras across the Cretaceous\Tertiary boundary.Discovery in Alaska of dinosaurs and mammals that lived at Late Cretaceous northern high latitudes provides evidence that many groups of terrestrial vertebrates had extensive geographic ranges and faunas were biogeographically differentiated. The Alaskan dinosaurs, represented by individuals that range in size from hatchlings to adults, might have been migratory forms living at high latitudes only during the summer months. In contrast, the small mammals probably were not migratory.Although recent discoveries are expanding our knowledge of the evolution of the terrestrial biota, the fossil record of terrestrial vertebrates during the Cretaceous\Tertiary transition is still heavily biased in favor of the northern Western Interior of North America. Here evolutionary change of the terrestrial fauna did not just involve extinction of lineages, some already decreasing in taxonomic diversity, and survival of many others. Shifts in biogeographic range and immigration of new groups played a significant role in remodeling the terrestrial fauna. The paleobotanical record is more extensive but also is biased with the most detailed record coming from the Western Interior where floral change is characterized as “massive” or “catastrophic” in scope.These conflicting evolutionary patterns are well founded being based on analysis of substantial fossil records. A new program of research directed toward resolution of the apparent paradox tests the hypothesis that at the end of the Cretaceous the terrestrial biota was biogeographically heterogeneous and evolutionary patterns of faunal and floral change in the Western Interior cannot be taken as globally representative.

scholarly journals Molecular clocks and the early evolution of metazoan nervous systems

2015 ◽  
Vol 370 (1684) ◽  
pp. 20150046 ◽  
Author(s):  
Gregory A. Wray
Keyword(s):  
Sensory Processing ◽  
Fossil Record ◽  
Sequence Data ◽  
Divergence Times ◽  
Molecular Clocks ◽  
Sense Organs ◽  
Animal Evolution ◽  
Nervous Systems ◽  
Nervous System Evolution ◽  
Fossil Records

The timing of early animal evolution remains poorly resolved, yet remains critical for understanding nervous system evolution. Methods for estimating divergence times from sequence data have improved considerably, providing a more refined understanding of key divergences. The best molecular estimates point to the origin of metazoans and bilaterians tens to hundreds of millions of years earlier than their first appearances in the fossil record. Both the molecular and fossil records are compatible, however, with the possibility of tiny, unskeletonized, low energy budget animals during the Proterozoic that had planktonic, benthic, or meiofaunal lifestyles. Such animals would likely have had relatively simple nervous systems equipped primarily to detect food, avoid inhospitable environments and locate mates. The appearance of the first macropredators during the Cambrian would have changed the selective landscape dramatically, likely driving the evolution of complex sense organs, sophisticated sensory processing systems, and diverse effector systems involved in capturing prey and avoiding predation.

Postembryonic development of Dalmanitina, and the evolution of facial suture fusion in Phacopina

Paleobiology ◽  
2018 ◽  
Vol 44 (4) ◽  
pp. 638-659
Author(s):  
Harriet B. Drage ◽  
Lukáš Laibl ◽  
Petr Budil
Keyword(s):  
Fossil Record ◽  
Postembryonic Development ◽  
Large Sample Size ◽  
Upper Ordovician ◽  
Geological Time ◽  
Fusion Event ◽  
Large Sample ◽  
Prague Basin ◽  
Suture Fusion ◽  
Insight Into

AbstractA large sample of postembryonic specimens of Dalmanitina proaeva elfrida and D. socialis from the Upper Ordovician (Sandbian to Katian) Prague Basin allows for the first reasonably complete ontogenetic sequence of Dalmanitoidea (Phacopina). The material provides an abundance of morphological information, including well-preserved marginal spines in protaspides and meraspides, and hypostome external surfaces throughout. The development of D. proaeva elfrida is unusual due to variability in timing of the first trunk articulation. This broadens our developmental understanding of Phacopina, a diverse group of phacopid trilobites, and also allows us to study the evolution of their specializations in exoskeletal molting behavior. Adult phacopines, unlike most other trilobites, had fused facial sutures. This means that rather than molting through the sutural gape mode, characterized by opening of the facial sutures and separation of the librigenae, they disarticulated the entire cephalon in Salter’s mode of molting. For other phacopine clades (Phacopoidea) the transition to Salter’s mode occurs during the meraspid period or at the onset of holaspis, and its developmental timing is intraspecifically fixed. However, owing to the large sample size, we can see that facial suture fusion likely occurred later in Dalmanitina, usually during the holaspid period, and was intraspecifically variable with holaspides of varying sizes showing unfused sutures. Further, D. proaeva elfrida specimens showed an initial librigenal–rostral plate fusion event, where the librigenae began as separate entities but appear fused with the rostral plate as one structure (the “lower cephalic unit”) from M1, and are discarded as such during molting. Dalmanitoidea is considered to represent the first phacopine divergence, occurring earliest in the fossil record. This material therefore provides insight into how linked morphologies and behaviors evolved, potentially suggesting the timing of facial suture fusion in Phacopina moved earlier during development and became more intraspecifically fixed over geological time.

Fossil flower of Staphylea L. from the Miocene amber of Mexico: New evidence of the Boreotropical Flora in low-latitude North America

2017 ◽  
Vol 108 (4) ◽  
pp. 471-478 ◽  
Author(s):  
Ana L. Hernández-Damián ◽  
Sergio R. S. Cevallos-Ferriz ◽  
Alma R. Huerta-Vergara
Keyword(s):  
North America ◽  
Northern Hemisphere ◽  
Fossil Record ◽  
First Record ◽  
High Latitudes ◽  
Low Latitude ◽  
Southern Mexico ◽  
Apparent Lack ◽  
History Of ◽  
New Evidence

ABSTRACTA new flower preserved in amber in sediments of Simojovel de Allende, México, is identified as an extinct member of Staphyleaceae, a family of angiosperms consisting of only three genera (Staphylea, Turpinia and Euscaphis), which has a large and abundant fossil record and is today distributed over the Northern Hemisphere. Staphylea ochoterenae sp. nov. is the first record of a flower for this group, which is small, pedicelled, pentamer, bisexual, with sepals and petals with similar size, dorsifixed anthers and superior ovary. Furthermore, the presence of stamens with pubescent filaments allows close comparison with extant flowers of Staphylea bulmada and S. forresti, species currently growing in Asia. However, their different number of style (one vs. three) and the apparent lack of a floral disc distinguish them from S. ochoterenae. The presence of Staphyleaceae in southern Mexico ca. 23 to 15My ago is evidence of the long history of integration of vegetation in low-latitude North America, in which some lineages, such as Staphylea, could move southwards from high latitudes of the Northern Hemisphere, as part of the Boreotropical Flora. In Mexico it grew in association with tropical elements, as suggested by the fossil record of the area.

Late Glacial and Holocene records of tree-killing conifer bark beetles in Europe and North America: Implications for forest disturbance dynamics

The Holocene ◽  
2020 ◽  
Vol 30 (6) ◽  
pp. 847-857 ◽  
Author(s):  
Nick Schafstall ◽  
Niina Kuosmanen ◽  
Christopher J Fettig ◽  
Miloš Knižek ◽  
Jennifer L Clear
Keyword(s):  
North America ◽  
Bark Beetle ◽  
Fossil Record ◽  
Bark Beetles ◽  
Late Glacial ◽  
Ips Paraconfusus ◽  
Distribution Data ◽  
Dryocoetes Confusus ◽  
Combining Data ◽  
Fossil Records

Outbreaks of conifer bark beetles in Europe and North America have increased in scale and severity in recent decades. In this study, we identify existing fossil records containing bark beetle remains from the end of the Last Glacial Maximum (~14,000 cal. yr BP) to present day using the online databases Neotoma and BugsCEP and literature searches, and compare these data with modern distribution data of selected tree-killing species. Modern-day observational data from the Global Biodiversity Information Facility (GBIF) database was used to map recorded distributions from AD 1750 to present day. A total of 53 fossil sites containing bark beetle remains, from both geological and archeological sites, were found during our searches. Fossil sites were fewer in Europe ( n = 21) than North America ( n = 32). In Europe, 29% of the samples in which remains were found were younger than 1000 cal. yr BP, while in North America, remains were mainly identified from late Glacial (~14,000–11,500 cal. yr BP) sites. In total, the fossil records contained only 8 of 20 species we consider important tree-killing bark beetles in Europe and North America based on their impacts during the last 100 years. In Europe, Ips sexdentatus was absent from the fossil record. In North America, Dendroctonus adjunctus, Dendroctonus frontalis, Dendroctonus jeffreyi, Dendroctonus pseudotsugae, Dryocoetes confusus, Ips calligraphus, Ips confusus, Ips grandicollis, Ips lecontei, Ips paraconfusus, and Scolytus ventralis were absent. Overall, preserved remains of tree-killing bark beetles are rare in the fossil record. However, by retrieving bulk material from new and existing sites and combining data from identified bark beetle remains with pollen, charcoal, tree rings, and geochemistry, the occurrence and dominance of bark beetles, their outbreaks, and other disturbance events can be reconstructed.

scholarly journals Unlocking the early fossil record of the arthropod central nervous system

2015 ◽  
Vol 370 (1684) ◽  
pp. 20150038 ◽  
Author(s):  
Gregory D. Edgecombe ◽  
Xiaoya Ma ◽  
Nicholas J. Strausfeld
Keyword(s):  
Fossil Record ◽  
Compound Eye ◽  
Three Dimensional ◽  
Taxonomic Diversity ◽  
Carbon Films ◽  
Burgess Shale ◽  
Temporal Window ◽  
Ground Pattern ◽  
Fine Grained ◽  
Central Nervous Systems

Extant panarthropods (euarthropods, onychophorans and tardigrades) are hallmarked by stunning morphological and taxonomic diversity, but their central nervous systems (CNS) are relatively conserved. The timing of divergences of the ground pattern CNS organization of the major panarthropod clades has been poorly constrained because of a scarcity of data from their early fossil record. Although the CNS has been documented in three-dimensional detail in insects from Cenozoic ambers, it is widely assumed that these tissues are too prone to decay to withstand other styles of fossilization or geologically older preservation. However, Cambrian Burgess Shale-type compressions have emerged as sources of fossilized brains and nerve cords. CNS in these Cambrian fossils are preserved as carbon films or as iron oxides/hydroxides after pyrite in association with carbon. Experiments with carcasses compacted in fine-grained sediment depict preservation of neural tissue for a more prolonged temporal window than anticipated by decay experiments in other media. CNS and compound eye characters in exceptionally preserved Cambrian fossils predict divergences of the mandibulate and chelicerate ground patterns by Cambrian Stage 3 ( ca 518 Ma), a dating that is compatible with molecular estimates for these splits.

Hidden diversity of small predators: new thorny lacewings from mid-Cretaceous amber from northern Myanmar (Neuroptera: Rhachiberothidae: Paraberothinae)

2020 ◽  
Vol 157 (7) ◽  
pp. 1149-1175 ◽  
Author(s):  
Hiroshi Nakamine ◽  
Shûhei Yamamoto ◽  
Yui Takahashi
Keyword(s):  
New Species ◽  
Northern Hemisphere ◽  
Morphological Variation ◽  
Phylogenetic Relationships ◽  
Fossil Record ◽  
Morphological Structure ◽  
Burmese Amber ◽  
Size Number ◽  
Fossil Records

AbstractThorny lacewings (Rhachiberothidae) are currently distributed only within Africa, whereas they are prevalent in the fossil record of various Cretaceous ambers across the Northern Hemisphere, with a handful of the fossil records from some Eocene European ambers. Four rhachiberothid species in four extinct genera are known from the mid-Cretaceous amber of northern Myanmar. Here, we report further examples of the remarkable palaeodiversity of this group from the same amber deposit, adding the four new fossil genera and seven new species: Acanthoberotha cuspis gen. et sp. nov., Astioberotha falcipes gen. et sp. nov., Stygioberotha siculifera gen. et sp. nov., Uranoberotha chariessa gen. et sp. nov., Creagroparaberotha cuneata sp. nov., Micromantispa galeata sp. nov. and M. spicata sp. nov. Based on a series of well-preserved specimens, we discuss the fine details of the raptorial forelegs and genital segments, which may be important for elucidating the phylogenetic relationships among genera. Our findings reveal an unexpectedly diverse assemblage of thorny lacewings in the Cretaceous System, highlighting the morphologically diverse rhachiberothids in Burmese amber. The discovery of seven additional rhachiberothid species in Myanmar amber suggests the potential for much higher diversity and abundance of the Cretaceous rhachiberothids than previously documented. Furthermore, morphological variation in the raptorial forelegs was found to be extremely diverse among the Burmese amber paraberothines, especially in terms of the size, number and shape of spines (or spine-like setae) on the inner edges of protibia, and the morphological structure of the probasitarsus.

Confidence intervals on stratigraphic ranges

Paleobiology ◽  
1990 ◽  
Vol 16 (1) ◽  
pp. 1-10 ◽  
Author(s):  
Charles R. Marshall
Keyword(s):  
Confidence Intervals ◽  
Fossil Record ◽  
Morphological Evolution ◽  
Radiometric Dating ◽  
Phylogenetic Hypotheses ◽  
Stratigraphic Ranges ◽  
Taxonomic Assignments ◽  
Fossil Records ◽  
Source Of Error ◽  
Stratigraphic Range

Observed stratigraphic ranges almost always underestimate true longevities. Strauss and Sadler (1987, 1989) provide a method for calculating confidence intervals on the endpoints of local stratigraphic ranges. Their method can also be applied to composite sections; confidence intervals may be placed on times of origin and extinction for entire species or lineages. Confidence interval sizes depend only on the length of the stratigraphic range and the number of fossil horizons. The technique's most important assumptions are that fossil horizons are distributed randomly and that collecting intensity has been uniform over the stratigraphic range. These assumptions are more difficult to test and less likely to be fulfilled for composite sections than for local sections.Confidence intervals give useful baseline estimates of the incompleteness of the fossil record, even if the underlying assumptions cannot be tested. Confidence intervals, which can be very large, should be calculated when the fossil record is used to assess absolute rates of molecular or morphological evolution, especially for poorly preserved groups. Confidence intervals have other functions: to determine how rich the fossil record has to be before radiometric dating errors become the dominant source of error in estimated times of origin or extinction; to predict future fossil finds; to predict which species with fossil records should be extant; and to assess phylogenetic hypotheses and taxonomic assignments.

SPECIATION AND NEUTRAL MOLECULAR EVOLUTION IN ONE-DIMENSIONAL CLOSED POPULATION

2003 ◽  
Vol 14 (07) ◽  
pp. 973-983 ◽  
Author(s):  
SERGEI V. SEMOVSKI ◽  
YURI S. BUKIN ◽  
DMITRY Yu. SHERBAKOV
Keyword(s):  
Molecular Evolution ◽  
Genetic Distance ◽  
Dna Sequence ◽  
Benthic Organisms ◽  
A Posteriori ◽  
Main Attention ◽  
Closed Population ◽  
One Dimensional ◽  
Phylogenetic Studies ◽  
Individual Based Models

Models are presented suitable for a description of speciation processes arising due to reproductive isolation depending on genetic distance. The main attention is paid to the model of a one-dimensional closed population, which describes the evolution of littoral benthic organisms. In order to correspond the modeling results to the results obtained in the course of experimental phylogenetic studies, all individual-based models described here involve neutrally evolving and maternally inherited DNA sequence. Sub-samples of the resulting sequences were used for a posteriori phylogenetic inferences which then were compared to the "true" evolutionary histories.

scholarly journals Oldest cingulate skulls provide congruence between morphological and molecular scenarios of armadillo evolution

2011 ◽  
Vol 278 (1719) ◽  
pp. 2791-2797 ◽  
Author(s):  
Guillaume Billet ◽  
Lionel Hautier ◽  
Christian de Muizon ◽  
Xavier Valentin
Keyword(s):  
Phylogenetic Analysis ◽  
Fossil Record ◽  
Phylogenetic Analyses ◽  
Typical Case ◽  
New Taxon ◽  
Late Oligocene ◽  
Phylogenetic Studies ◽  
Molecular Phylogenetic ◽  
Early Neogene ◽  
Group A

The cingulates of the mammalian order Xenarthra present a typical case of disagreement between molecular and morphological phylogenetic studies. We report here the discovery of two new skulls from the Late Oligocene Salla Beds of Bolivia (approx. 26 Ma), which are the oldest known well-preserved cranial remains of the group. A new taxon is described: Kuntinaru boliviensis gen. et sp. nov. A phylogenetic analysis clusters K. boliviensis together with the armadillo subfamily Tolypeutinae. These skulls document an early spotty occurrence for the Tolypeutinae at 26 Ma, in agreement with the temporal predictions of previous molecular studies. The fossil record of tolypeutines is now characterized by a unique occurrence in the Late Oligocene, and a subsequent 12 Myr lack in the fossil record. It is noteworthy that the tolypeutines remain decidedly marginal in the Late Palaeogene and Early Neogene deposits, whereas other cingulate groups diversify. Also, the anatomical phylogenetic analysis herein, which includes K. boliviensis , is congruent with recent molecular phylogenetic analyses. Kuntinaru boliviensis is the oldest confident calibration point available for the whole Cingulata.

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