The Birds from Las Hoyas

2002 ◽  
Vol 85 (2) ◽  
pp. 113-130 ◽  
Author(s):  
José Luis Sanz ◽  
Francisco Ortega
Keyword(s):  
Early Cretaceous ◽  
Evolutionary History ◽  
Morphological Changes ◽  
General View ◽  
Evolutionary Transition ◽  
Avian Flight ◽  
Theropod Dinosaurs ◽  
Fossil Material ◽  
Life Habits ◽  
Wing Aspect Ratio

Information on the first steps of the avian evolutionary history has dramatically increased during the last few years. The fossil record provides a general view of the morphological changes of the avian flight apparatus from non-volant ancestors (non-avian theropod dinosaurs) to the first derived fliers of the Early Cretaceous. The Las Hoyas bird record includes three genera: Iberomesornis, Concornis and Eoalulavis. This fossil material has yielded information about the early avian evolutionary history. These Early Cretaceous birds (some 120 Myr old) had a wingbeat cycle and breathing devices similar to those of extant birds. The function of the rectricial fan was also similar. In the evolutionary transition from cursorial ancestors to derived fliers it is possible to verify a trend to increase lift. Primitive wing aspect ratio morphotypes were elliptical ones, other derived morphotypes appeared, for example, in the Neornithes (extant birds). Some primitive fliers, like the Las Hoyas genus Eoalulavis, had an alula (feathers attached to the first digit of the hand) similar to that of present day birds, indicating braking and manoeuvring skills similar to those of their extant relatives. Primitive avian life habits are poorly understood. Some evidence from the Las Hoyas bird record indicates that Early Cretaceous birds were present in the trophic chains.

scholarly journals The early evolution of feathers: fossil evidence from Cretaceous amber of France

2008 ◽  
Vol 275 (1639) ◽  
pp. 1197-1202 ◽  
Author(s):  
Vincent Perrichot ◽  
Loïc Marion ◽  
Didier Néraudeau ◽  
Romain Vullo ◽  
Paul Tafforeau
Keyword(s):  
Early Cretaceous ◽  
Developmental Stages ◽  
Critical Stage ◽  
Avian Flight ◽  
Early Bird ◽  
Theropod Dinosaurs ◽  
Fossil Evidence ◽  
Developmental Theories ◽  
Incremental Evolution ◽  
Fossil Records

The developmental stages of feathers are of major importance in the evolution of body covering and the origin of avian flight. Until now, there were significant gaps in knowledge of early morphologies in theoretical stages of feathers as well as in palaeontological material. Here we report fossil evidence of an intermediate and critical stage in the incremental evolution of feathers which has been predicted by developmental theories but hitherto undocumented by evidence from both the recent and the fossil records. Seven feathers have been found in an Early Cretaceous (Late Albian, ca 100 Myr) amber of western France, which display a flattened shaft composed by the still distinct and incompletely fused bases of the barbs forming two irregular vanes. Considering their remarkably primitive features, and since recent discoveries have yielded feathers of modern type in some derived theropod dinosaurs, the Albian feathers from France might have been derived either from an early bird or from a non-avian dinosaur.

scholarly journals Integration and diversity of the caviomorph mandible (Rodentia: Hystricomorpha): assessing the evolutionary history through fossils and ancestral shape reconstructions

2019 ◽  
Vol 188 (1) ◽  
pp. 276-301 ◽  
Author(s):  
Alicia Álvarez ◽  
Marcos D Ercoli ◽  
Diego H Verzi
Keyword(s):  
Evolutionary History ◽  
Middle Eocene ◽  
Morphological Changes ◽  
Feeding Habits ◽  
Shape Variation ◽  
Phylogenetic Structure ◽  
Geometric Morphometric ◽  
History Of ◽  
Life Habits ◽  
Functional Units

Abstract Caviomorph rodents constitute a highly diverse clade of Neotropical mammals. They are recorded since at least the late Middle Eocene and have a long and complex evolutionary history. Using geometric morphometric data, we analysed the variation in mandibular shape of this clade through integration analyses, allometry and shape optimizations onto a phylogenetic tree of 104 extant and extinct species. The analyses of shape variation revealed a strong influence of phylogenetic structure and life habits. A remarkable allometric effect was observed for specific mandibular traits. Morphological changes occurring in the alveolar and muscular functional units were moderately associated. Interestingly, the coordinated evolution of these two functional units was decoupled in the clade of extant abrocomids. A sequential and nearly synchronic acquisition of convergent traits has occurred in chinchillids and derived cavioids since at least the early Middle Oligocene, probably derived from grass-feeding habits or similar adaptations to other abrasive items. Convergences between fossorial taxa evolved in two main events through the Oligocene and middle Late Miocene. Morphological analysis of the fossil representatives allowed a better understanding of the timing of trait acquisitions during the evolutionary history of caviomorphs and its relationship with global and regional palaeoenvironmental changes.

scholarly journals A Middle Jurassic abelisaurid from Patagonia and the early diversification of theropod dinosaurs

2012 ◽  
Vol 279 (1741) ◽  
pp. 3170-3175 ◽  
Author(s):  
Diego Pol ◽  
Oliver W. M. Rauhut
Keyword(s):  
South America ◽  
Northern Hemisphere ◽  
Early Cretaceous ◽  
Middle Jurassic ◽  
Evolutionary History ◽  
Regional Geography ◽  
Distinctive Features ◽  
Theropod Dinosaurs ◽  
Early Diversification ◽  
History Of

Abelisaurids are a clade of large, bizarre predatory dinosaurs, most notable for their high, short skulls and extremely reduced forelimbs. They were common in Gondwana during the Cretaceous, but exceedingly rare in the Northern Hemisphere. The oldest definitive abelisaurids so far come from the late Early Cretaceous of South America and Africa, and the early evolutionary history of the clade is still poorly known. Here, we report a new abelisaurid from the Middle Jurassic of Patagonia, Eoabelisaurus mefi gen. et sp. nov., which predates the so far oldest known secure member of this lineage by more than 40 Myr. The almost complete skeleton reveals the earliest evolutionary stages of the distinctive features of abelisaurids, such as the modification of the forelimb, which started with a reduction of the distal elements. The find underlines the explosive radiation of theropod dinosaurs in the Middle Jurassic and indicates an unexpected diversity of ceratosaurs at that time. The apparent endemism of abelisauroids to southern Gondwana during Pangean times might be due to the presence of a large, central Gondwanan desert. This indicates that, apart from continent-scale geography, aspects such as regional geography and climate are important to reconstruct the biogeographical history of Mesozoic vertebrates.

scholarly journals Soft-tissue and dermal arrangement in the wing of an Early Cretaceous bird: Implications for the evolution of avian flight

2015 ◽  
Vol 5 (1) ◽  
Author(s):  
Guillermo Navalón ◽  
Jesús Marugán-Lobón ◽  
Luis M. Chiappe ◽  
José Luis Sanz ◽  
Ángela D. Buscalioni
Keyword(s):  
Soft Tissue ◽  
Early Cretaceous ◽  
Avian Flight

scholarly journals Endocast of the Late Triassic (Carnian) dinosaur Saturnalia tupiniquim: implications for the evolution of brain tissue in Sauropodomorpha

2018 ◽  
Author(s):  
Mario Bronzati ◽  
Oliver W M Rauhut ◽  
Jonathas S Bittencourt ◽  
Max C. Langer
Keyword(s):  
South America ◽  
Brain Tissue ◽  
Evolutionary History ◽  
Morphological Changes ◽  
Volume Reduction ◽  
Late Triassic ◽  
History Of

The evolutionary history of dinosaurs might date back to the fist stages of the Triassic (c. 250– 240 Ma), but the oldest unequivocal records of the group come from Late Triassic (Carnian – c. 230 Ma) rocks of South America. Here, we present the fist braincase endocast of a Carnian dinosaur, the sauropodomorph Saturnalia tupiniquim, and provide new data regarding the evolution of the flccular and paraflccular lobe of the cerebellum (FFL), which has been extensively discussed in the fild of palaeoneurology. Previous studies proposed that the development of a permanent quadrupedal stance was one of the factors leading to the volume reduction of the FFL of sauropods. However, based on the new data for S. tupiniquim we identifid a fist moment of FFL volume reduction in nonsauropodan Sauropodomorpha, preceding the acquisition of a fully quadrupedal stance. Analysing variations in FFL volume alongside other morphological changes in the group, we suggest that this reduction is potentially related to the adoption of a more restricted herbivore diet. In this context, the FFL of sauropods might represent a vestigial trait, retained in a reduced version from the bipedal and predatory early sauropodomorphs.

Amber

2014 ◽  
Vol 20 ◽  
pp. 163-216 ◽  
Author(s):  
Conrad C. Labandeira
Keyword(s):  
Early Cretaceous ◽  
Phase 1 ◽  
Insect Pest ◽  
Phylogenetic Reconstruction ◽  
Plant Host ◽  
Pest Outbreaks ◽  
Ancient Proteins ◽  
Life Habits ◽  
Biotic Effects ◽  
Wood Boring

The amber fossil record provides a distinctive, 320-million-year-old taphonomic mode documenting gymnosperm, and later, angiosperm, resin-producing taxa. Resins and their subfossil (copal) and fossilized (amber) equivalents are categorized into five classes of terpenoid, phenols, and other compounds, attributed to extant family-level taxa. Copious resin accumulations commencing during the early Cretaceous are explained by two hypotheses: 1) abundant resin production as a byproduct of plant secondary metabolism, and 2) induced and constitutive host defenses for warding off insect pest and pathogen attack through profuse resin production. Forestry research and fossil wood-boring damage support a causal relationship between resin production and pest attack. Five stages characterize taphonomic conversion of resin to amber: 1) Resin flows initially caused by biotic or abiotic plant-host trauma, then resin flowage results from sap pressure, resin viscosity, solar radiation, and fluctuating temperature; 2) entrapment of live and dead organisms, resulting in 3) entombment of organisms; then 4) movement of resin clumps to 5) a deposition site. This fivefold diagenetic process of amberization results in resin→copal→amber transformation from internal biological and chemical processes and external geological forces. Four phases characterize the amber record: a late Paleozoic Phase 1 begins resin production by cordaites and medullosans. A pre-mid-Cretaceous Mesozoic Phase 2 provides increased but still sparse accumulations of gymnosperm amber. Phase 3 begins in the mid-early Cretaceous with prolific amber accumulation likely caused by biotic effects of an associated fauna of sawflies, beetles, and pathogens. Resiniferous angiosperms emerge sporadically during the late Cretaceous, but promote Phase 4 through their Cenozoic expansion. Throughout Phases 3 and 4, the amber record of trophic interactions involves parasites, parasitoids, and perhaps transmission of diseases, such as malaria. Other recorded interactions are herbivory, predation, pollination, phoresy, and mimicry. In addition to litter, amber also captures microhabitats of wood and bark, large sporocarps, dung, carrion, phytotelmata, and resin substrates. These microhabitats are differentially represented; the primary taphonomic bias is size, and then the sedentary vs. wandering life habits of organisms. Organismic abundance from lekking, ant-refuse heaps, and pest outbreaks additionally contribute to bias. Various techniques are used to image and analyze amber, allowing assessment of: 1) ancient proteins; 2) phylogenetic reconstruction; 3) macroevolutionary patterns; and 4) paleobiogeographic distributions. Three major benefits result from study of amber fossil material, in contrast to three different benefits of compression-impression fossils.

scholarly journals Current perspectives on the evolution of birds

2008 ◽  
Vol 77 (2) ◽  
pp. 109-116 ◽  
Author(s):  
Per G.P. Ericson
Keyword(s):  
Evolutionary History ◽  
Genetic Data ◽  
Morphological Characters ◽  
Current Understanding ◽  
Sources Of Information ◽  
Theropod Dinosaurs ◽  
History Of ◽  
Evolution Of Birds ◽  
The Many ◽  
Rapid Radiations

The paper summarizes the current understanding of the evolution and diversification of birds. New insights into this field have mainly come from two fundamentally different, but complementary sources of information: the many newly discovered Mesozoic bird fossils and the wealth of genetic analyses of living birds at various taxonomic levels. The birds have evolved from theropod dinosaurs from which they can be defined by but a few morphological characters. The early evolutionary history of the group is characterized by the extinctions of many major clades by the end of the Cretaceous, and by several periods of rapid radiations and speciation. Recent years have seen a growing consensus about the higher-level relationships among living birds, at least as can be deduced from genetic data.

The first potential fossil record of a dibamid reptile (Squamata: Dibamidae): a new taxon from the early Oligocene of Central Mongolia

2019 ◽  
Vol 187 (3) ◽  
pp. 782-799 ◽  
Author(s):  
Andrej Čerňanský
Keyword(s):  
Fossil Record ◽  
Evolutionary History ◽  
Phylogenetic Analyses ◽  
New Taxon ◽  
Unique Combination ◽  
Central Mongolia ◽  
Squamate Reptiles ◽  
The Past ◽  
Early Oligocene ◽  
Fossil Material

Abstract Dibamid reptiles have a known current distribution on two continents (Asia and North America). Although this clade represents an early-diverging group in the Squamata and thus should have a long evolutionary history, no fossil record of these peculiar burrowing squamate reptiles has been documented so far. The fossil material described here comes from the early Oligocene of the Valley of Lakes in Central Mongolia. This material consists of jaws and is placed in the clade Dibamidae on the basis of its morphology, which is further confirmed by phylogenetic analyses. In spite of the fragmentary nature of this material, it thus forms the first, but putative, fossil evidence of this clade. If correctly interpreted, this material demonstrates the occurrence of Dibamidae in East Asia in the Palaeogene, indicating its distribution in higher latitudes than today. The preserved elements possess a unique combination of character states, and a new taxon name is therefore erected: Hoeckosaurus mongoliensis sp. nov. The dentary of Hoeckosaurus exhibits some characters of the two extant dibamid taxa. However, the open Meckel’s groove, together with other characters, show that this group was morphologically much more diverse in the past.

scholarly journals Extreme diversity and parasitism of Late Jurassic squat lobsters (Decapoda: Galatheoidea) and the oldest records of porcellanids and galatheids

2019 ◽  
Vol 187 (4) ◽  
pp. 1131-1154 ◽  
Author(s):  
Cristina M Robins ◽  
Adiël A Klompmaker
Keyword(s):  
Early Cretaceous ◽  
Late Jurassic ◽  
Evolutionary History ◽  
Common Species ◽  
Statistical Analyses ◽  
Decapod Crustaceans ◽  
Squat Lobsters

AbstractGalatheoid decapod crustaceans consist of ~1250 species today, but their evolutionary history and origin are poorly known. We studied the largest known fossil galatheoid assemblage, from the Late Jurassic of Ernstbrunn, Austria. This coral-associated assemblage yielded 2348 specimens, arranged in 53 species, 22 genera and six families. Rarefaction analyses show that nearly all taxa have been collected. In addition to abundant Munidopsidae, this assemblage also contains the oldest members of four of the six galatheoid families, including Galatheidae, Munididae, Paragalatheidae and Porcellanidae. We describe the oldest Porcellanidae and Galatheidae to date, and a catillogalatheid: Vibrissalana jurassica gen. et sp. nov., ?Galathea genesis sp. nov. and Galatheites britmelanarum sp. nov. Our re-examination of the oldest claimed porcellanid, Jurellana tithonia, from Ernstbrunn, indicates that it represents a homolodromioid brachyuran, ascribed to Jurellanidae fam. nov. along with Ovalopus gen. nov. The second-oldest claimed porcellanid, Early Cretaceous Petrolisthes albianicus, is transferred to the catillogalatheid Hispanigalathea. We further document that 10.4% of Ernstbrunn galatheoid specimens were parasitized by epicaridean isopods, as shown by swellings in the gill region. Statistical analyses indicate that infestation is near non-random, varying from 0 to 33% for common species. Thus, Late Jurassic coral-associated habitats were key ecosystems in the evolution of galatheoids and their parasites.

Taphonomic bias and the evolutionary history of the family Cidaridae (Echinodermata: Echinoidea)

Paleobiology ◽  
1992 ◽  
Vol 18 (1) ◽  
pp. 50-79 ◽  
Author(s):  
Benjamin J. Greenstein
Keyword(s):  
Type Species ◽  
Evolutionary History ◽  
Middle Triassic ◽  
Upper Jurassic ◽  
Late Triassic ◽  
Type Specimens ◽  
Fossil Material ◽  
Group I ◽  
The Family ◽  
History Of

The class Echinoidea apparently originated during the Ordovician Period and diversified slowly through the Paleozoic Era. The clade then mushroomed in diversity beginning in Late Triassic time and continued expanding into the present. Although this evolutionary history is generally accepted, the taphonomic overprint affecting it has not been explored. To gain a more accurate perception of the evolutionary history of the group, I have compared the diversity history of the family Cidaridae (Echinodermata: Echinoidea) with the preservational style of fossil type species using literature-derived data. The Cidaridae apparently originated in Middle Triassic time and diversified slowly through the Neocomian (Early Cretaceous). Diversity was maintained through the remainder of the Cretaceous and Tertiary Periods, reflecting the diversity history of the subclass. Characterization of the preservational style of type fossil material for the family revealed the following breakdown of preservational states: 60% of species were described on the basis of disarticulated skeletal material, primarily spines; 20% based on intact coronas denuded of spines, apical system, Aristotle's lantern and peristomial plates; 10% based on large coronal fragments; and 10% based on other skeletal elements. This distribution may represent the effect of a disarticulation threshold on the condition of echinoid carcasses before final burial and suggests that preservation of intact specimens may be very unlikely. For cidaroids, previous work has suggested that this threshold is likely to be reached after 7 days of decay.Comparison of the diversity history of the Cidaridae with the preservation data reveals that characteristic patterns of taphonomic overprint have affected the group since its origination in Middle Triassic time, and the nature of that overprint has changed over time: the early diversity history of the group is characterized by occurrences of fragmented fossil material, with spines predominant; further radiation of the group in mid-Jurassic time coincided with an increase in modes of preservation, ranging between exceptionally well-preserved material and disarticulated skeletal elements. Finally, type material is more rarely described from younger stratigraphic intervals (Miocene–Pleistocene) and consists predominantly of disarticulated skeletal elements and coronal fragments larger than an interambulacrum in size. Intact, denuded coronas are noticeably lacking.The number of type species of Cidaridae described in each stratigraphic interval has not been consistent during post-Paleozoic time. Middle Triassic, Malm (Upper Jurassic), Senonian (Upper Cretaceous) and Eocene series yielded significantly (α = .05) higher numbers of type specimens per million years, while the Lias (Lower Jurassic), Dogger (Mid-Jurassic), Lower Cretaceous and Paleocene yielded significantly (α = .05) lower numbers of type specimens per million years. This may be the result of a combination of taxonomic, sampling, and geographical biases.

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