scholarly journals Antiquity and fundamental processes of the antler cycle in Cervidae (Mammalia)

2020 ◽  
Vol 108 (1) ◽  
Author(s):  
Gertrud E. Rössner ◽  
Loïc Costeur ◽  
Torsten M. Scheyer
Keyword(s):  
Empirical Data ◽  
Fossil Record ◽  
Middle Miocene ◽  
Growth Patterns ◽  
Growth Modes ◽  
Regular Cycle ◽  
Antler Cycle ◽  
Insight Into

AbstractThe origins of the regenerative nature of antlers, being branched and deciduous apophyseal appendages of frontal bones of cervid artiodactyls, have long been associated with permanent evolutionary precursors. In this study, we provide novel insight into growth modes of evolutionary early antlers. We analysed a total of 34 early antlers affiliated to ten species, including the oldest known, dating from the early and middle Miocene (approx. 18 to 12 million years old) of Europe. Our findings provide empirical data from the fossil record to demonstrate that growth patterns and a regular cycle of necrosis, abscission and regeneration are consistent with data from modern antlers. The diverse histological analyses indicate that primary processes and mechanisms of the modern antler cycle were not gradually acquired during evolution, but were fundamental from the earliest record of antler evolution and, hence, explanations why deer shed antlers have to be rooted in basic histogenetic mechanisms. The previous interpretation that proximal circular protuberances, burrs, are the categorical traits for ephemerality is refuted.

scholarly journals Antiquity and fundamental processes of the antler cycle in Cervidae (Mammalia)

2020 ◽  
Author(s):  
Gertrud E. Rössner ◽  
Loïc Costeur ◽  
Torsten M. Scheyer
Keyword(s):  
Empirical Data ◽  
Fossil Record ◽  
Middle Miocene ◽  
Growth Patterns ◽  
Growth Modes ◽  
Regular Cycle ◽  
Antler Cycle ◽  
Insight Into

AbstractThe origins of the regenerative nature of antlers, being branched and deciduous apophyseal appendages of frontal bones of cervid artiodactyls, have long been associated with permanent evolutionary precursors. In this study, we provide novel insight into growth modes of evolutionary early antlers. We analysed a total of 34 early antlers affiliated to ten species, including the oldest known, dating from the early and middle Miocene (approx. 19 to 12 million years old) of Europe. Our findings provide empirical data from the fossil record to demonstrate that growth patterns and a regular cycle of necrosis, abscission and regeneration are consistent with data from modern antlers. The diverse histological analyses indicate that primary processes and mechanisms of the modern antler cycle were not gradually acquired during evolution, but were fundamental from the earliest record of antler evolution and, hence, explanations why deer shed antlers have to be rooted in basic histogenetic mechanisms.

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.

scholarly journals Women's Participation in the Australian Digital Content Industry

2014 ◽  
pp. 125-142
Author(s):  
Anitza Geneve
Keyword(s):  
Agency Theory ◽  
Empirical Data ◽  
Causal Effect ◽  
Digital Content ◽  
Women's Participation ◽  
Digital Content Industry ◽  
Australian Case ◽  
The Rich ◽  
Insight Into

There is a need to understand the phenomenon of women's under-representation in the Australian Digital Content Industry (DCI) workforce. This chapter presents the findings from an Australian case study where both women working in the industry and industry stakeholders were interviewed for their insight into the influences on women's participation. The rich empirical data and findings from the case study are interpreted using the Acts of Agency theory—an original theory by the author of this chapter. As the chapter reveals there are five ‘Acts of Agency' (containing 10 agent-driven mechanisms) identified as influencing women's participation. Agent-driven mechanisms recognise the causal effect of people themselves; that is, the role individuals play in their participation.

scholarly journals Early fossil record of Euarthropoda and the Cambrian Explosion

2018 ◽  
Vol 115 (21) ◽  
pp. 5323-5331 ◽  
Author(s):  
Allison C. Daley ◽  
Jonathan B. Antcliffe ◽  
Harriet B. Drage ◽  
Stephen Pates
Keyword(s):  
Fossil Record ◽  
Trace Fossils ◽  
Cambrian Explosion ◽  
Burgess Shale ◽  
Crown Group ◽  
Total Group ◽  
Stem Lineage ◽  
Coherent Picture ◽  
Insight Into ◽  
Phosphate Deposits

Euarthropoda is one of the best-preserved fossil animal groups and has been the most diverse animal phylum for over 500 million years. Fossil Konservat-Lagerstätten, such as Burgess Shale-type deposits (BSTs), show the evolution of the euarthropod stem lineage during the Cambrian from 518 million years ago (Ma). The stem lineage includes nonbiomineralized groups, such as Radiodonta (e.g., Anomalocaris) that provide insight into the step-by-step construction of euarthropod morphology, including the exoskeleton, biramous limbs, segmentation, and cephalic structures. Trilobites are crown group euarthropods that appear in the fossil record at 521 Ma, before the stem lineage fossils, implying a ghost lineage that needs to be constrained. These constraints come from the trace fossil record, which show the first evidence for total group Euarthropoda (e.g., Cruziana, Rusophycus) at around 537 Ma. A deep Precambrian root to the euarthropod evolutionary lineage is disproven by a comparison of Ediacaran and Cambrian lagerstätten. BSTs from the latest Ediacaran Period (e.g., Miaohe biota, 550 Ma) are abundantly fossiliferous with algae but completely lack animals, which are also missing from other Ediacaran windows, such as phosphate deposits (e.g., Doushantuo, 560 Ma). This constrains the appearance of the euarthropod stem lineage to no older than 550 Ma. While each of the major types of fossil evidence (BSTs, trace fossils, and biomineralized preservation) have their limitations and are incomplete in different ways, when taken together they allow a coherent picture to emerge of the origin and subsequent radiation of total group Euarthropoda during the Cambrian.

Insight into the structure and morphology of Run clusters on Co(111) and Co(311) surfaces

2018 ◽  
Vol 8 (10) ◽  
pp. 2728-2739 ◽  
Author(s):  
Lili Liu ◽  
Mengting Yu ◽  
Qiang Wang ◽  
Bo Hou ◽  
Yan Liu ◽  
...  
Keyword(s):  
Density Functional Theory ◽  
Dft Calculations ◽  
Density Functional ◽  
Fischer Tropsch ◽  
Functional Theory ◽  
Fischer Tropsch Synthesis ◽  
Structure And Morphology ◽  
Growth Modes ◽  
Ru Promoter ◽  
Insight Into

The adsorption configurations, growth modes and morphology of a Ru promoter under the approximate conditions of cobalt catalyzed Fischer–Tropsch synthesis (FTS) were investigated by density functional theory (DFT) calculations.

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.

Theoretical diversity of the marine biosphere

Paleobiology ◽  
2010 ◽  
Vol 36 (1) ◽  
pp. 1-15 ◽  
Author(s):  
Michał Kowalewski ◽  
Seth Finnegan
Keyword(s):  
Empirical Data ◽  
Fossil Record ◽  
Empirical Studies ◽  
Geological History ◽  
Empirical Knowledge ◽  
Primary Target ◽  
History Of ◽  
Global Biodiversity ◽  
Theoretical Considerations ◽  
Marine Biosphere

In considering the history of biodiversity paleontologists have focused on exploratory investigations of empirical data derived from the fossil record. Starting with the pioneering work of Philips (1860), and continuing at an increasing pace through today, this inductive approach has dominated diversity research. In contrast, deductive theoretical considerations that focus on the expected history of biodiversity, and develop independently of empirical knowledge, have remained under-explored. Appreciating the need for a nomothetic paleobiology (Gould 1980), we here reconsider the history of biodiversity, using deductive models constrained by a few, self-evident parameters. This analysis centers on the marine fossil record, the primary target of most previous empirical studies on the geological history of global biodiversity (e.g., Valentine 1969; Raup 1972, 1976; Sepkoski et al. 1981; Alroy et al. 2008).

Taxonomic review of two fossil crocodylians from the Cenozoic of South America and its implications for the crocodylian fauna of the continent

Zootaxa ◽  
2019 ◽  
Vol 4656 (3) ◽  
pp. 475-486
Author(s):  
GIOVANNE M. CIDADE ◽  
DANIEL FORTIER ◽  
ASCANIO DANIEL RINCÓN ◽  
ANNIE SCHMALTZ HSIOU
Keyword(s):  
South America ◽  
Fossil Record ◽  
Middle Miocene ◽  
Taxonomic Status ◽  
Junior Synonym ◽  
Diverse Group ◽  
Taxonomic Review ◽  
Nomen Dubium ◽  
Extant Species ◽  
The World

The crocodylomorph fauna of the Cenozoic of South America is one of the richest and most diverse in the world. The most diverse group within that fauna is Alligatoroidea, with nearly all of its species belonging to the Caimaninae clade. Many of the fossil alligatoroid species from the Cenozoic of South America were proposed based on very incomplete remains, and as a result their validity requires revision. Two such species are Balanerodus logimus Langston, 1965, from the middle Miocene of Colombia and Peru, and Caiman venezuelensis Fortier & Rincón, 2012, from the Pliocene-Pleistocene of Venezuela. This study has performed a thorough review of the taxonomic status of these two alligatoroid species, concluding that B. logimus is a nomen dubium and that Ca. venezuelensis is a junior synonym of the extant species Ca. crocodilus. This review offers a significantly more accurate scenario for alligatoroid diversity in the Cenozoic of South America in different epochs such as the Miocene and Pleistocene. Additionally, the record of Ca. crocodilus from the Pleistocene of Venezuela is the first fossil record that can be assigned to this species. 

scholarly journals Osteohistological analyses reveal diverse strategies of theropod dinosaur body-size evolution

2020 ◽  
Vol 287 (1939) ◽  
pp. 20202258
Author(s):  
Thomas M. Cullen ◽  
Juan I. Canale ◽  
Sebastián Apesteguía ◽  
Nathan D. Smith ◽  
Dongyu Hu ◽  
...  
Keyword(s):  
Fossil Record ◽  
Weight Bearing ◽  
Growth Patterns ◽  
Growth Strategies ◽  
Theropod Dinosaur ◽  
Physiological Constraints ◽  
Size Evolution ◽  
Acceleration Model ◽  
Extensive Growth ◽  
Body Size Evolution

The independent evolution of gigantism among dinosaurs has been a topic of long-standing interest, but it remains unclear if gigantic theropods, the largest bipeds in the fossil record, all achieved massive sizes in the same manner, or through different strategies. We perform multi-element histological analyses on a phylogenetically broad dataset sampled from eight theropod families, with a focus on gigantic tyrannosaurids and carcharodontosaurids, to reconstruct the growth strategies of these lineages and test if particular bones consistently preserve the most complete growth record. We find that in skeletally mature gigantic theropods, weight-bearing bones consistently preserve extensive growth records, whereas non-weight-bearing bones are remodelled and less useful for growth reconstruction, contrary to the pattern observed in smaller theropods and some other dinosaur clades. We find a heterochronic pattern of growth fitting an acceleration model in tyrannosaurids, with allosauroid carcharodontosaurids better fitting a model of hypermorphosis. These divergent growth patterns appear phylogenetically constrained, representing extreme versions of the growth patterns present in smaller coelurosaurs and allosauroids, respectively. This provides the first evidence of a lack of strong mechanistic or physiological constraints on size evolution in the largest bipeds in the fossil record and evidence of one of the longest-living individual dinosaurs ever documented.

scholarly journals Debris-carrying camouflage among diverse lineages of Cretaceous insects

2016 ◽  
Vol 2 (6) ◽  
pp. e1501918 ◽  
Author(s):  
Bo Wang ◽  
Fangyuan Xia ◽  
Michael S. Engel ◽  
Vincent Perrichot ◽  
Gongle Shi ◽  
...  
Keyword(s):  
Fossil Record ◽  
Morphological Characteristics ◽  
Early Evolution ◽  
Behavioral Repertoire ◽  
Wood Fibers ◽  
Morphological Adaptations ◽  
Evolutionary Success ◽  
High Degree ◽  
Insect Assemblage ◽  
Insight Into

Insects have evolved diverse methods of camouflage that have played an important role in their evolutionary success. Debris-carrying, a behavior of actively harvesting and carrying exogenous materials, is among the most fascinating and complex behaviors because it requires not only an ability to recognize, collect, and carry materials but also evolutionary adaptations in related morphological characteristics. However, the fossil record of such behavior is extremely scarce, and only a single Mesozoic example from Spanish amber has been recorded; therefore, little is known about the early evolution of this complicated behavior and its underlying anatomy. We report a diverse insect assemblage of exceptionally preserved debris carriers from Cretaceous Burmese, French, and Lebanese ambers, including the earliest known chrysopoid larvae (green lacewings), myrmeleontoid larvae (split-footed lacewings and owlflies), and reduviids (assassin bugs). These ancient insects used a variety of debris material, including insect exoskeletons, sand grains, soil dust, leaf trichomes of gleicheniacean ferns, wood fibers, and other vegetal debris. They convergently evolved their debris-carrying behavior through multiple pathways, which expressed a high degree of evolutionary plasticity. We demonstrate that the behavioral repertoire, which is associated with considerable morphological adaptations, was already widespread among insects by at least the Mid-Cretaceous. Together with the previously known Spanish specimen, these fossils are the oldest direct evidence of camouflaging behavior in the fossil record. Our findings provide a novel insight into early evolution of camouflage in insects and ancient ecological associations among plants and insects.

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