scholarly journals Predicting Evolutionary Transitions in Tooth Complexity With a Morphogenetic Model

2019 ◽  
Author(s):  
Aidan M. C. Couzens ◽  
Karen E. Sears ◽  
Martin Rücklin
Keyword(s):  
Fossil Record ◽  
Morphological Character ◽  
Fine Tuning ◽  
Evolutionary Transitions ◽  
Anatomical Structures ◽  
Dietary Adaptation ◽  
Developmental Parameters ◽  
Discontinuous Variation ◽  
Evolutionary Trajectories ◽  
Enamel Knots

AbstractThe extent to which evolutionary transitions are shaped by developmental bias remains poorly understood. Classically, morphological variation is assumed to be abundant and continuous, but if morphogenesis biases how traits vary than evolutionary transitions might follow somewhat predictable steps. Compared to other anatomical structures, teeth have an exceptional fossil record which documents striking evolutionary trajectories toward complexity. Using computer simulations of tooth morphogenesis, we examined how varying developmental parameters influenced transitions from morphologically simple to complex teeth. We find that as tooth complexity increases, development tends to generate progressively more discontinuous variation which could make the fine-tuning of dietary adaptation difficult. Transitions from simple to complex teeth required an early shift from mesiodistal to lateral cusp patterning which is congruent with patterns of dental complexification in early mammals. We infer that the contributions of primary enamel knot cells to secondary enamel knots which are responsible for patterning lateral cusps may have been an important developmental innovation in tribosphenic mammals. Our results provide evidence that development can bias evolutionary transitions and highlights how morphogenetic modelling can play an important role in building more realistic models of morphological character evolution.

scholarly journals Otomorphs (= otocephalans or ostarioclupeomorphs) revisited

2018 ◽  
Vol 16 (3) ◽  
Author(s):  
Gloria Arratia
Keyword(s):  
Fossil Record ◽  
Morphological Character ◽  
Neotropical Region ◽  
Morphological Features ◽  
Heterogeneous Group ◽  
Vertebral Centra ◽  
Molecular Studies ◽  
Gas Bladder ◽  
Parietal Bones ◽  
Freshwater Environments

ABSTRACT A morphological revision is presented here on the cohort Otomorpha, a clade currently interpreted as the most primitive among the large supercohort Clupeocephala. Otomorpha is a morphologically heterogeneous group represented by clupei forms , alepocephaliforms, and ostariophysans (gonorynchiforms, cypriniforms, characiforms, siluriforms, and gymnoti forms) that inhabit various marine and freshwater environments worldwide. Otomorphs have a long (ca. 145 Ma) and diverse fossil record. They are the largest fish teleostean clade worldwide, as well as the largest of the Neotropical Region. While molecular studies strongly confirm the monophyly of Otomorpha, most potential morphological synapomorphies of the group become homoplastic largely due to the peculiar morphological character states (either losses or transformations) present in alepocephaliforms. The fusion of haemal arches with their respective vertebral centra anterior to preural centrum 2 stands as an unambiguous synapomorphy of the clade. The ankylosis or fusion of the extrascapular and parietal bones, and silvery areas associated with the gas bladder are also interpreted as synapomorphies, although they are homoplastic characters mainly due to secondary losses or further transformations of the morphological features in the alepocephaliforms.

scholarly journals Improvements in the fossil record may largely resolve current conflicts between morphological and molecular estimates of mammal phylogeny

2018 ◽  
Vol 285 (1893) ◽  
pp. 20181632 ◽  
Author(s):  
Robin M. D. Beck ◽  
Charles Baillie
Keyword(s):  
Maximum Likelihood ◽  
Fossil Record ◽  
Morphological Character ◽  
Phylogenetic Analyses ◽  
Molecular Data ◽  
Morphological Data ◽  
Ancestral State ◽  
Case Scenario ◽  
State Reconstruction ◽  
Consensus View

Phylogenies of mammals based on morphological data continue to show several major areas of conflict with the current consensus view of their relationships, which is based largely on molecular data. This raises doubts as to whether current morphological character sets are able to accurately resolve mammal relationships. We tested this under a hypothetical ‘best case scenario’ by using ancestral state reconstruction (under both maximum parsimony and maximum likelihood) to infer the morphologies of fossil ancestors for all clades present in a recent comprehensive DNA sequence-based phylogeny of mammals, and then seeing what effect the subsequent inclusion of these predicted ancestors had on unconstrained phylogenetic analyses of morphological data. We found that this resulted in topologies that are highly congruent with the current consensus phylogeny, at least when the predicted ancestors are assumed to be well preserved and densely sampled. Most strikingly, several analyses recovered the monophyly of clades that have never been found in previous morphology-only studies, such as Afrotheria and Laurasiatheria. Our results suggest that, at least in principle, improvements in the fossil record—specifically the discovery of fossil taxa that preserve the ancestral or near-ancestral morphologies of the nodes in the current consensus—may be sufficient to largely reconcile morphological and molecular estimates of mammal phylogeny, even using current morphological character sets.

Complex regional pain syndrome following lateral lumbar interbody fusion

2013 ◽  
Vol 19 (4) ◽  
pp. 502-506 ◽  
Author(s):  
Simon Morr ◽  
Adam S. Kanter
Keyword(s):  
Complex Regional Pain Syndrome ◽  
Interbody Fusion ◽  
Surgical Techniques ◽  
Pain Syndrome ◽  
Fine Tuning ◽  
Review Of The Literature ◽  
Anatomical Structures ◽  
Transpsoas Approach ◽  
Surgical Corridor ◽  
Lumbar Spinal

The minimally destructive lateral transpsoas approach to the spine has been used in the treatment of various lumbar spinal pathologies. Approach-specific complications have been reported due to the unique surgical corridor and lateral anatomical structures. The authors report a case of complex regional pain syndrome (CRPS) following interbody cage placement utilizing the lateral lumbar transpsoas approach. A review of the literature is discussed. Further clarification of the mechanism of CRPS and its treatments remains crucial for the fine-tuning of novel surgical techniques and complication avoidance during the development of these techniques.

scholarly journals Cladogenesis and replacement in the fossil record of Microsyopidae (?Primates) from the southern Bighorn Basin, Wyoming

2021 ◽  
Vol 17 (2) ◽  
Author(s):  
Mary T. Silcox ◽  
Keegan R. Selig ◽  
Thomas M. Bown ◽  
Amy E. Chew ◽  
Kenneth D. Rose
Keyword(s):  
Fossil Record ◽  
Evolutionary Change ◽  
Local Extinction ◽  
Bighorn Basin ◽  
Early Eocene ◽  
Evolutionary Transitions ◽  
Continuous Record ◽  
Extinction Event ◽  
Nearly Continuous

The early Eocene of the southern Bighorn Basin, Wyoming, is notable for its nearly continuous record of mammalian fossils. Microsyopinae (?Primates) is one of several lineages that shows evidence of evolutionary change associated with an interval referred to as Biohorizon A. Arctodontomys wilsoni is replaced by a larger species, Arctodontomys nuptus , during the biohorizon interval in what is likely an immigration/emigration or immigration/local extinction event. The latter is then superseded by Microsyops angustidens after the end of the Biohorizon A interval. Although this pattern has been understood for some time, denser sampling has led to the identification of a specimen intermediate in morphology between A. nuptus and M. angustidens , located stratigraphically as the latter is appearing. Because specimens of A. nuptus have been recovered approximately 60 m above the appearance of M. angustidens , it is clear that A. nuptus did not suffer pseudoextinction. Instead, evidence suggests that M. angustidens branched off from a population of A. nuptus , but the latter species persisted. This represents possible evidence of cladogenesis, which has rarely been directly documented in the fossil record. The improved understanding of both evolutionary transitions with better sampling highlights the problem of interpreting gaps in the fossil record as punctuations.

Evolution of mammalian biology

2004 ◽  
Author(s):  
T.S. Kemp
Keyword(s):  
Fossil Record ◽  
Vertebral Column ◽  
The Body ◽  
Evolutionary Transitions ◽  
Highly Sensitive ◽  
Jaw Musculature ◽  
Very High ◽  
Insight Into ◽  
Biological Differences ◽  
Considerable Insight

There are large biological differences between the mammals and the primitive living amniotes as represented by turtles, lizards, and crocodiles ● Differentiated dentition with occluding post-canine teeth, and radical reorganisation of jaw musculature to operate them ● Differentiation of vertebral column and limb musculature, and repositioning of limbs to bring feet under the body, increasing agility of locomotion ● Relatively huge brain and highly sensitive sense organs ● Endothermic temperature physiology, with very high metabolic rates, insulation, and high respiratory rates ● Precise osmoregulatory and chemoregulatory abilities using loops of Henle in the kidney and an array of endocrine mechanisms Incomplete as it is, the fossil record of the mammal-like reptiles, or ‘non-mammalian synapsids’ permits the reconstruction of a series of hypothetical intermediate stages that offers considerable insight into how, when, and where this remarkable transition occurred. Deriving these stages starts with a cladogram of the relevant fossils that is then read as an evolutionary tree, with hypothetical ancestors represented by the nodes. The characters that define a node, plus the characters of the previous nodes, constitute the reconstruction. The differences in characters between adjacent nodes represent the evolutionary transitions that by inference occurred, and the whole set of successive nodes generates all that can be inferred about the sequence of acquisition of characters. If a hypothetical ancestral synapsid is placed at the base of the cladogram, and a hypothetical ancestral mammal as the final node, then the set of nodes in between represents everything the fossil record is capable of revealing about the pattern by which mammalian characters evolved: the sequence of their acquisition, the correlations between characters, and possibly the rates of their evolution. Of course, the inferred pattern of evolution of characters is only as reliable as the cladogram which generated it, and that in turn is only as realistic as the model of evolution used in its construction from the character data. And of course, there must have been many intermediate stages in the transition than cannot be reconstructed for want of appropriate fossil representation of those particular grades. Nevertheless, limited as it may be, this is what can be known from the fossil record.

scholarly journals A unique winged euthycarcinoid from the Permian of Antarctica

2017 ◽  
Vol 91 (5) ◽  
pp. 987-993
Author(s):  
Joseph H. Collette ◽  
John L. Isbell ◽  
Molly F. Miller
Keyword(s):  
Fossil Record ◽  
Trace Fossil ◽  
Morphological Similarity ◽  
Evolutionary Transitions ◽  
Body Segments ◽  
Rapid Transition ◽  
Proglacial Lake ◽  
High Degree ◽  
Freshwater Environments

AbstractEuthycarcinoid arthropods (Cambrian–Triassic) were likely the first animals to transition from oceanic to freshwater and emergent environments. Although their basic bauplan is well known, they have a poor fossil record because their non-sclerotized exoskeleton was rarely preserved. Euthycarcinoids’ unusual morphology (varying numbers of body segments, seemingly dichotomous possession of either mandibles or a labrum, specialized or generalized limbs, and possession by some euthycarcinoid species of sternal pores—structures possibly analogous to coxal vesicles in myriapods) contribute to uncertainty regarding their relationship to other arthropod groups; while their poor fossil record masks the evolutionary transitions within and between the separate realms they inhabited (marine, freshwater, emergent). A new euthycarcinoid from a Permian polar proglacial lake is described herein that is morphologically unlike all other euthycarcinoids, and interpreted as being well adapted for a nekton-benthic lifestyle. Antarcticarcinus pagoda n. gen. n. sp. possesses a pair of large wing-like processes that project laterally from the preabdominal dorsal exoskeleton. A trace fossil from the overlying Mackellar Formation, cf. Orbiculichnus, which was previously interpreted as having been produced by insects taking off or landing on wet sediments, is reinterpreted herein as being produced by A. pagoda n. gen. n. sp. due to the high degree of morphological similarity between traces and body fossils. This occurrence indicates that euthycarcinoids were able to adapt to life in temperate freshwater environments, while possible subaerial adaptations hint at an ability to breathe air. Indeed, if euthycarcinoids could breathe air, Cambrian terrestrial forays and rapid transition (by the Ordovician) into freshwater environments might be explained.

scholarly journals Enzyme Evolution: An Epistatic Ratchet versus a Smooth Reversible Transition

2019 ◽  
Vol 37 (4) ◽  
pp. 1133-1147 ◽  
Author(s):  
Moshe Ben-David ◽  
Misha Soskine ◽  
Artem Dubovetskyi ◽  
Kesava-Phaneendra Cherukuri ◽  
Orly Dym ◽  
...  
Keyword(s):  
Crystal Structures ◽  
Active Site ◽  
Molecular Simulations ◽  
Unique Sequence ◽  
Paraoxonase 1 ◽  
Evolutionary Transitions ◽  
Laboratory Evolution ◽  
Catalytic Residues ◽  
Reversible Transition ◽  
Evolutionary Trajectories

Abstract Evolutionary trajectories are deemed largely irreversible. In a newly diverged protein, reversion of mutations that led to the functional switch typically results in loss of both the new and the ancestral functions. Nonetheless, evolutionary transitions where reversions are viable have also been described. The structural and mechanistic causes of reversion compatibility versus incompatibility therefore remain unclear. We examined two laboratory evolution trajectories of mammalian paraoxonase-1, a lactonase with promiscuous organophosphate hydrolase (OPH) activity. Both trajectories began with the same active-site mutant, His115Trp, which lost the native lactonase activity and acquired higher OPH activity. A neo-functionalization trajectory amplified the promiscuous OPH activity, whereas the re-functionalization trajectory restored the native activity, thus generating a new lactonase that lacks His115. The His115 revertants of these trajectories indicated opposite trends. Revertants of the neo-functionalization trajectory lost both the evolved OPH and the original lactonase activity. Revertants of the trajectory that restored the original lactonase function were, however, fully active. Crystal structures and molecular simulations show that in the newly diverged OPH, the reverted His115 and other catalytic residues are displaced, thus causing loss of both the original and the new activity. In contrast, in the re-functionalization trajectory, reversion compatibility of the original lactonase activity derives from mechanistic versatility whereby multiple residues can fulfill the same task. This versatility enables unique sequence-reversible compositions that are inaccessible when the active site was repurposed toward a new function.

scholarly journals Fossils and living taxa agree on patterns of body mass evolution: a case study with Afrotheria

2015 ◽  
Vol 282 (1821) ◽  
pp. 20152023 ◽  
Author(s):  
Mark N. Puttick ◽  
Gavin H. Thomas
Keyword(s):  
Body Mass ◽  
Fossil Record ◽  
Morphological Character ◽  
Morphological Evolution ◽  
Evolutionary Model ◽  
The Body ◽  
Evolutionary Patterns ◽  
Size Evolution ◽  
Body Size Evolution

Most of life is extinct, so incorporating some fossil evidence into analyses of macroevolution is typically seen as necessary to understand the diversification of life and patterns of morphological evolution. Here we test the effects of inclusion of fossils in a study of the body size evolution of afrotherian mammals, a clade that includes the elephants, sea cows and elephant shrews. We find that the inclusion of fossil tips has little impact on analyses of body mass evolution; from a small ancestral size (approx. 100 g), there is a shift in rate and an increase in mass leading to the larger-bodied Paenungulata and Tubulidentata, regardless of whether fossils are included or excluded from analyses. For Afrotheria, the inclusion of fossils and morphological character data affect phylogenetic topology, but these differences have little impact upon patterns of body mass evolution and these body mass evolutionary patterns are consistent with the fossil record. The largest differences between our analyses result from the evolutionary model, not the addition of fossils. For some clades, extant-only analyses may be reliable to reconstruct body mass evolution, but the addition of fossils and careful model selection is likely to increase confidence and accuracy of reconstructed macroevolutionary patterns.

scholarly journals Oxynaspididae (Crustacea, Cirripedia): phylogenetics and evolutionary ecology, with descriptions of three new genera and six new species

Zootaxa ◽  
2011 ◽  
Vol 3103 (1) ◽  
pp. 1
Author(s):  
ROBERT J. VAN SYOC ◽  
ALLEN M. DEKELBOUM
Keyword(s):  
Phylogenetic Analysis ◽  
New Species ◽  
Fossil Record ◽  
Morphological Character ◽  
Evolutionary Ecology ◽  
New Genera ◽  
Single Specimen ◽  
Species Ranges

A phylogenetic analysis of the Cirripedia family Oxynaspididae yields four monophyletic clades. These are designated as four genera, Oxynaspis Darwin, 1852, Archoxynaspis gen. nov., Pycnaspis gen. nov. and Minyaspis gen. nov. Five new species from Astrolabe Reef in Fiji (Oxynaspis perekrestenkoi sp. nov., O. joankovanae sp. nov., Minyaspis amylaneae sp. nov., M. opreskoi sp. nov. and M. welchi sp. nov.) and one from Palau (Oxynaspis joandianae sp. nov.) are described. A morphological character dataset and resulting phylogeny supporting the new generic divisions is presented. All but two of the 24 species previously known and all six of the newly described species are intimately associated with antipatharians. Pycnaspis connectens was described by Broch (1931) as “fixed to a silicious sponge.” A list of species’ ranges and their known hosts is presented. The earliest known possible antipatharian in the fossil record is Miocene, much later than the Eocene appearance of Archoxynaspis eocenica (Withers, 1935). Therefore, the symbiosis of oxynaspidids with antipatharians may have evolved only since the Miocene. However, given the dubious fossil record of antipatharians (known only from a single specimen of uncertain affinity from Miocene Italy) the time of the first antipatharian/oxynaspidid symbiosis is uncertain.

scholarly journals ‘Do larger molars and robust jaws in early hominins represent dietary adaptation?’ A New Study in Tooth Wear

2013 ◽  
Vol No. 16 (2012-2013) ◽  
Author(s):  
Anna Clement ◽  
Simon Hillson
Keyword(s):  
Stable Isotopes ◽  
Fossil Record ◽  
Tooth Wear ◽  
Dental Microwear ◽  
Alternative Source ◽  
Dietary Adaptation ◽  
Early Hominin ◽  
First Time ◽  
Source Of Information ◽  
Lines Of Evidence

Diet imposes significant constraints on the biology and behaviour of animals. The fossil record suggests that key changes in diet have taken place throughout the course of human evolution. Defining these changes enables us to understand the behaviour of our extinct fossil ancestors. Several lines of evidence are available for studying the diet of early hominins, including craniodental morphology, palaeoecology, dental microwear and stable isotopes. They do, however, often provide conflicting results. Using dental macrowear analysis, this new UCL Institute of Archaeology project will provide an alternative source of information on early hominin diet. Dental macrowear has often been used to analyse diet in archaeological populations, but this will be the first time that this type of detailed study has been applied to the early hominin fossil record.

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