The Divergent Evolution of Arthropod Brains

2018 ◽  
pp. 30-70 ◽  
Author(s):  
Nicholas J. Strausfeld
Keyword(s):  
Nervous System ◽  
Evolutionary History ◽  
Sedimentary Rocks ◽  
Divergent Evolution ◽  
Comparative Neuroanatomy ◽  
Middle Cambrian ◽  
Major Transitions ◽  
Horseshoe Crabs ◽  
History Of ◽  
Living Species

Occasionally, fossils recovered from lower and middle Cambrian sedimentary rocks contain the remains of nervous system. These residues reveal the symmetric arrangements of brain and ganglia that correspond to the ground patterns of brain and ventral ganglia of four major panarthropod clades existing today: Onychophora, Chelicerata, Myriapoda, and Pancrustacea. Comparative neuroanatomy of living species and studies of fossils suggest that highly conserved neuronal arrangements have been retained in these four lineages for more than a half billion years, despite some major transitions of neuronal architectures. This chapter will review recent explorations into the evolutionary history of the arthropod brain, concentrating on the subphylum Pancrustacea, which comprises hexapods and crustaceans, and on the subphylum Chelicerata, which includes horseshoe crabs, scorpions, and spiders. Studies of Pancrustacea illustrate some of the challenges in ascribing homology to centers that appear to have corresponding organization, whereas Chelicerata offers clear examples of both divergent cerebral evolution and convergence.

Geochronology of the Belt Series, Montana

1968 ◽  
Vol 5 (3) ◽  
pp. 737-747 ◽  
Author(s):  
J. D. Obradovich ◽  
Z. E. Peterman
Keyword(s):  
Average Rate ◽  
Sedimentary Rocks ◽  
Time Interval ◽  
Depositional History ◽  
Middle Cambrian ◽  
Basement Rocks ◽  
Field Evidence ◽  
Minimum Age ◽  
History Of ◽  
Central Montana

This paper presents new radiometric data that permit some qualified statements to be made on the depositional history of the Belt sedimentary rocks. The period of deposition of sedimentary rocks of the Precambrian Belt Series has been placed within a broad time interval, for they rest on metamorphosed basement rock dated at ~ 1800 m.y. and are overlain by the Middle Cambrian Flathead Quartzite (circa 530 m.y.). Prior geochronometric data gathered during the last decade indicate most of the Belt Series to be older than ~ 1100 m.y.K–Ar and Rb–Sr techniques have been applied recently to a variety of samples selected from the whole gamut of the Belt Series. Glauconite from various formations in the sequence McNamara Formation down to the uppermost beds of the Empire Formation in the Sun River area has been dated at 1080 ± 27 m.y. by the K–Ar method and at 1095 ± 22 m.y. by the Rb–Sr mineral isochron method. A Rb–Sr whole-rock isochron based on argillaceous sedimentary rocks from this 5000-ft section gives an age of 1100 ± 53 m.y. The concordance of the preceding results and the K–Ar ages (1075 to 1110 m.y.) on Purcell sills and lava imply that this age represents the time of sedimentation of these units.A Rb–Sr isochron based on whole-rock samples stratigraphically far below the Umpire Formation— the Greyson Shale, Newland Limestone, Chamberlain Shale, and Neihart Quartzite in the Big Belt and Little Beit Mountains—yields an age of 1325 ± 15 m.y. This result is interpreted as indicating a substantial unconformity beneath the Belt Series, at least in central Montana; it also suggests a major hiatus, unsuspected from field evidence, between the uppermost part of the Empire Formation and the Greyson Shale.The results for the youngest of Belt rocks—the Pilcher Quartzite and the Garnet Range Formation, which are exposed in the Alberton region—are equivocal in that there is widespread dispersion. A large component of detrital muscovite in some of the samples could readily account for the magnitude and sense of this dispersion. A maximum age of ~930 m.y. based on an isochron of minimum slope through the various points may be inferred for this sequence. A K–Ar age of 760 m.y. obtained on biotite from a sill in the Garnet Range Formation provides a minimum age for these younger Belt rocks.Three distinct periods of sedimentation for Belt rocks sampled are suggested at ≥ 1300, 1100, and ≤ 900 m.y., with two substantial hiatuses of 200 m.y. or more. In addition the data for the sequence in the Big and Little Belt Mountains suggest that sedimentation may not have commenced for a period of possibly 400 m.y. after the metamorphism that affected basement rocks, while the data for the Garnet Range and Pilcher sequence suggest that sedimentation ceased some 200 to 400 m.y. prior to the deposition of the Middle Cambrian Flathead Quartzite.To suggest that the Belt sediments were deposited continuously over a period of 400 m.y. or more would imply an unusually low average rate of deposition of ≤ 0.1 ft/1000 yr, and this for the thickest part of the Belt Series. As a realistic expression of the depositional history of the Belt Series, both viewpoints are open to question, but the viewpoint that the Belt basin has been characterized by discontinuous sedimentation would be more in keeping with the principle of uniformity.

scholarly journals Waptia fieldensis Walcott, a mandibulate arthropod from the middle Cambrian Burgess Shale

2018 ◽  
Vol 5 (6) ◽  
pp. 172206 ◽  
Author(s):  
Jean Vannier ◽  
Cédric Aria ◽  
Rod S. Taylor ◽  
Jean-Bernard Caron
Keyword(s):  
Evolutionary History ◽  
The Body ◽  
Formal Description ◽  
Front Part ◽  
Burgess Shale ◽  
Middle Cambrian ◽  
History Of ◽  
Ellipsoid Bodies ◽  
Active Swimming ◽  
Prey Items

Waptia fieldensis Walcott, 1912 is one of the iconic animals from the middle Cambrian Burgess Shale biota that had lacked a formal description since its discovery at the beginning of the twentieth century. This study, based on over 1800 specimens, finds that W. fieldensis shares general characteristics with pancrustaceans, as previous authors had suggested based mostly on its overall aspect. The cephalothorax is covered by a flexible, bivalved carapace and houses a pair of long multisegmented antennules, palp-bearing mandibles, maxillules, and four pairs of appendages with five-segmented endopods—the anterior three pairs with long and robust enditic basipods, the fourth pair with proximal annulations and lamellae. The post-cephalothorax has six pairs of lamellate and fully annulated appendages which appear to be extensively modified basipods rather than exopods. The front part of the body bears a pair of stalked eyes with the first ommatidia preserved in a Burgess Shale arthropod, and a median ‘labral’ complex flanked by lobate projections with possible affinities to hemi-ellipsoid bodies. Waptia confirms the mandibulate affinity of hymenocarines, retrieved here as part of an expanded Pancrustacea, thereby providing a novel perspective on the evolutionary history of this hyperdiverse group. We construe that Waptia was an active swimming predator of soft prey items, using its anterior appendages for food capture and manipulation, and also potentially for clinging to epibenthic substrates.

Human Evolution

1984 ◽  
Vol 8 ◽  
pp. 182-198
Author(s):  
Catherine Badgley
Keyword(s):  
Human Evolution ◽  
Evolutionary History ◽  
Pan Paniscus ◽  
Homo Sapiens ◽  
Great Apes ◽  
Sister Group ◽  
The Family ◽  
History Of ◽  
Living Species ◽  
Single Living

The evolutionary history of humans is well understood in outline, compared to that of many other groups of mammals. But human evolution remains enigmatic in its details, and these are compelling both scientifically and personally because they relate to the biological uniqueness of humans. Humans are placed in the primate family Hominidae, which, in traditional classifications, contains a single living species, Homo sapiens. The closest living relatives of humans are great apes: the chimpanzees Pan paniscus and Pan troglodytes, the gorilla Gorilla gorilla, and the orangutan Pongo pygmaeus. These apes have traditionally been placed in the family Pongidae as the sister group of Hominidae. Living Hominidae and Pongidae, together with Hylobatidae (gibbons) comprise the modern representatives of the primate suborder Hominoidea.

scholarly journals Ancient origins and multiple appearances of carotenoid-pigmented feathers in birds

2014 ◽  
Vol 281 (1788) ◽  
pp. 20140806 ◽  
Author(s):  
Daniel B. Thomas ◽  
Kevin J. McGraw ◽  
Michael W. Butler ◽  
Matthew T. Carrano ◽  
Odile Madden ◽  
...  
Keyword(s):  
Raman Spectroscopy ◽  
High Performance ◽  
Evolutionary History ◽  
Carotenoid Pigments ◽  
Biological Functions ◽  
The Family ◽  
Family Level ◽  
History Of ◽  
Living Species ◽  
Insight Into

The broad palette of feather colours displayed by birds serves diverse biological functions, including communication and camouflage. Fossil feathers provide evidence that some avian colours, like black and brown melanins, have existed for at least 160 million years (Myr), but no traces of bright carotenoid pigments in ancient feathers have been reported. Insight into the evolutionary history of plumage carotenoids may instead be gained from living species. We visually surveyed modern birds for carotenoid-consistent plumage colours (present in 2956 of 9993 species). We then used high-performance liquid chromatography and Raman spectroscopy to chemically assess the family-level distribution of plumage carotenoids, confirming their presence in 95 of 236 extant bird families (only 36 family-level occurrences had been confirmed previously). Using our data for all modern birds, we modelled the evolutionary history of carotenoid-consistent plumage colours on recent supertrees. Results support multiple independent origins of carotenoid plumage pigmentation in 13 orders, including six orders without previous reports of plumage carotenoids. Based on time calibrations from the supertree, the number of avian families displaying plumage carotenoids increased throughout the Cenozoic, and most plumage carotenoid originations occurred after the Miocene Epoch (23 Myr). The earliest origination of plumage carotenoids was reconstructed within Passeriformes, during the Palaeocene Epoch (66–56 Myr), and not at the base of crown-lineage birds.

Cephalochordate Nervous System

2018 ◽  
Author(s):  
Simona Candiani ◽  
Mario Pestarino
Keyword(s):  
Experimental Data ◽  
Nervous System ◽  
Evolutionary History ◽  
Molecular Methods ◽  
Neuronal Circuits ◽  
Serotonergic Neurons ◽  
Nervous Systems ◽  
System P ◽  
History Of ◽  
Peripheral Nervous Systems

The central and peripheral nervous systems of amphioxus adults and larvae are characterized by morphofunctional features relevant to understanding the origins and evolutionary history of the vertebrate CNS. Classical neuroanatomical studies are mainly on adult amphioxus, but there has been a recent focus, both by TEM and molecular methods, on the larval CNS. The latter is small and remarkably simple, and new data on the localization of glutamatergic, GABAergic/glycinergic, cholinergic, dopaminergic, and serotonergic neurons within the larval CNS are now available. In consequence, it has been possible begin the process of identifying specific neuronal circuits, including those involved in controlling larval locomotion. This is especially useful for the insights it provides into the organization of comparable circuits in the midbrain and hindbrain of vertebrates. A much better understanding of basic chordate CNS organization will eventually be possible when further experimental data will emerge.

Study of the Early Telencephalon Genes of Cyclostomes as a Way to Restoring the Evolutionary History of This Unique Part of the Central Nervous System of Vertebrates

2021 ◽  
Vol 55 (7) ◽  
pp. 752-765
Author(s):  
G. V. Ermakova ◽  
A. V. Kucheryavyy ◽  
F. M. Eroshkin ◽  
N. Yu. Martynova ◽  
A. G. Zaraisky ◽  
...  
Keyword(s):  
Central Nervous System ◽  
Nervous System ◽  
Evolutionary History ◽  
History Of ◽  
The Central Nervous System ◽  
Unique Part

scholarly journals Neural development in Eucidaris tribuloides and the evolutionary history of the echinoid larval nervous system

2013 ◽  
Vol 377 (1) ◽  
pp. 236-244 ◽  
Author(s):  
Cory D. Bishop ◽  
Katelyn E.A. MacNeil ◽  
Digna Patel ◽  
Valerie J. Taylor ◽  
Robert D. Burke
Keyword(s):  
Nervous System ◽  
Neural Development ◽  
Evolutionary History ◽  
Larval Nervous System ◽  
History Of

scholarly journals Evolution of Multicellularity

Genes ◽  
2021 ◽  
Vol 12 (10) ◽  
pp. 1532
Author(s):  
J. Mark Cock
Keyword(s):  
Evolutionary History ◽  
Major Transitions ◽  
History Of ◽  
Multicellular Organisms

The emergence of multicellular organisms was, perhaps, the most spectacular of the major transitions during the evolutionary history of life on this planet [...]

scholarly journals Basal polyphagan beetles in mid-Cretaceous amber from Myanmar: biogeographic implications and long-term morphological stasis

2019 ◽  
Vol 286 (1894) ◽  
pp. 20182175 ◽  
Author(s):  
Chenyang Cai ◽  
John F. Lawrence ◽  
Shûhei Yamamoto ◽  
Richard A. B. Leschen ◽  
Alfred F. Newton ◽  
...  
Keyword(s):  
Evolutionary History ◽  
Geological Time ◽  
Burmese Amber ◽  
Incertae Sedis ◽  
Morphological Stasis ◽  
New Synonym ◽  
Extant Species ◽  
History Of ◽  
Living Species

The origin and early evolutionary history of polyphagan beetles have been largely based on evidence from the derived and diverse ‘core Polyphaga’, whereas little is known about the species-poor basal polyphagan lineages, which include Scirtoidea (Clambidae, Decliniidae, Eucinetidae, and Scirtidae) and Derodontidae. Here, we report two new species Acalyptomerus thayerae sp. nov. and Sphaerothorax uenoi sp. nov., both belonging to extant genera of Clambidae, from mid-Cretaceous Burmese amber. Acalyptomerus thayerae has a close affinity to A. herbertfranzi , a species currently occurring in Mesoamerica and northern South America. Sphaerothorax uenoi is closely related to extant species of Sphaerothorax , which are usually collected in forests of Nothofagus of Australia, Chile, and New Zealand. The discovery of two Cretaceous species from northern Myanmar indicates that both genera had lengthy evolutionary histories, originated at least by the earliest Cenomanian, and were probably more widespread than at present. Remarkable morphological similarities between fossil and living species suggest that both genera changed little over long periods of geological time. The long-term persistence of similar mesic microhabitats such as leaf litter may account for the 99 Myr morphological stasis in Acalyptomerus and Sphaerothorax . Additionally, the extinct staphylinoid family Ptismidae is proposed as a new synonym of Clambidae, and its only included species Ptisma zasukhae is placed as incertae sedis within Clambidae.

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