scholarly journals Life history of a basal bird: morphometrics of the Early Cretaceous Confuciusornis

2008 ◽  
Vol 4 (6) ◽  
pp. 719-723 ◽  
Author(s):  
Luis M Chiappe ◽  
Jesús Marugán-Lobón ◽  
Shu'an Ji ◽  
Zhonghe Zhou
Keyword(s):  
Life History ◽  
Sexual Dimorphism ◽  
Exponential Growth ◽  
Growth Stage ◽  
Sexual Size Dimorphism ◽  
Growth Patterns ◽  
Morphometric Study ◽  
Size Dimorphism ◽  
Caudal Vertebrae ◽  
History Of

Confuciusornis sanctus stands out among the remarkable diversity of Mesozoic birds recently unearthed from China. Not only is this primitive beaked pygostylian (birds with abbreviated caudal vertebrae fused into a pygostyle) much more abundant than other avian taxa of this age but differences in plumage between specimens—some having a pair of long stiff tail feathers—have been interpreted as evidence for the earliest example of sexual dimorphism in birds. We report the results of a multivariate morphometric study involving measurements of more than 100 skeletons of C. sanctus . Our analyses do not show any correlation between size distribution and the presence or absence of blade-like rectrices (tail feathers), thus implying, that if these feathers are sexual characters, they are not correlated with sexual size dimorphism. Our results also provide insights into the taxonomy and life history of confuciusornithids, suggesting that these birds may have retained ancestral dinosaurian growth patterns characterized by a midlife exponential growth stage.

scholarly journals Life history, sexual dimorphism and ‘ornamental’ feathers in the mesozoic bird Confuciusornis sanctus

2009 ◽  
Vol 5 (6) ◽  
pp. 817-820 ◽  
Author(s):  
Winfried S. Peters ◽  
Dieter Stefan Peters
Keyword(s):  
Life History ◽  
Sexual Size Dimorphism ◽  
Size Spectrum ◽  
Bimodal Size Distribution ◽  
Size Dimorphism ◽  
Sexual Dimorphisms ◽  
Male Trait ◽  
Extant Species ◽  
History Of ◽  
Available Information

The life history of Confuciusornis sanctus is controversial. Recently, the species’ body size spectrum was claimed to contradict osteohistological evidence for a rapid, bird-like development. Moreover, sexual size dimorphism was rejected as an explanation for the observed bimodal size distribution since the presence of elongated rectrices, an assumed ‘male’ trait, was uncorrelated with size. However, this interpretation (i) fails to explain the size spectrum of C. sanctus which is trimodal rather than bimodal, (ii) requires implausible neonate masses and (iii) is not supported by analogy with sexual dimorphisms in modern birds, in which elongated central rectrices are mostly sex-independent. Available information on C. sanctus is readily reconciled if we assume a bird-like life history, as well as a pronounced sexual size dimorphism and sexually isomorphic extravagant feathers as frequently observed in extant species.

Sexual size dimorphism and life history traits in an island-mainland system: an overview of the lizard genus Microlophus

2021 ◽  
pp. 1-7
Author(s):  
Ken S. Toyama ◽  
Christopher K. Boccia
Keyword(s):  
Life History ◽  
South America ◽  
Life History Theory ◽  
Life History Traits ◽  
Sexual Size Dimorphism ◽  
Life History Strategies ◽  
Galápagos Islands ◽  
Size Dimorphism ◽  
Rensch's Rule ◽  
Comprehensive Compilation

Abstract Opposing life history strategies are a common result of the different ecological settings experienced by insular and continental species. Here we present a comprehensive compilation of data on sexual size dimorphism (SSD) and life history traits of Microlophus, a genus of lizards distributed in western South America and the Galápagos Islands, and test for differences between insular and continental species under life history theory expectations. Contrary to our predictions, we found no differences in SSD between localities or evidence that Microlophus follows Rensch’s rule. However, as expected, head dimensions and maturity sizes were significantly larger in insular species while continental species had larger clutches. Our results show that Microlophus exhibits some of the patterns expected from an island-mainland system, but unexplained patterns will only be resolved through future ecological, morphological and behavioural studies integrating both faunas.

Life on the edge: the ecology and life history of the tropidurine iguanid lizard Uranoscodon superciliosum

1990 ◽  
Vol 68 (7) ◽  
pp. 1366-1373 ◽  
Author(s):  
Jeffrey M. Howland ◽  
Laurie J. Vitt ◽  
Pamela T. Lopez
Keyword(s):  
Life History ◽  
Social Interaction ◽  
Sexual Dimorphism ◽  
Small Diameter ◽  
Habitat Specialization ◽  
Large Size ◽  
Tropical Wet Forest ◽  
History Of ◽  
Forest Streams ◽  
Small Forest

An Amazonian population of the iguanid lizard Uranoscodon superciliosum was studied in lowland tropical wet forest in central Pará, Brazil. These nonheliothermic lizards are restricted to densely vegetated habitats near (often over) water, particularly riverbanks and small forest streams, where they utilize small-diameter perches and feed on a wide variety of invertebrates, apparently at the water's edge. They mature at moderate to large size at an age of about 1.5 years. Production of moderate-sized clutches of eggs is seasonal, and reproduction and fat storage both cycle in association with rainfall and flooding. Although they occur in fairly high densities, social interaction is uncommon and sexual dimorphism is not pronounced. The ecology and life history of this lizard seem to be strongly influenced by the unusual habitat specialization.

Sexual size dimorphism in the viviparous caecilian amphibian Geotrypetes seraphini seraphini (Gymnophiona: Dermophiidae) including an updated overview of sexual dimorphism in caecilian amphibians

2016 ◽  
Vol 37 (3) ◽  
pp. 291-299 ◽  
Author(s):  
Markus Maerker ◽  
Sandy Reinhard ◽  
Peter Pogoda ◽  
Alexander Kupfer
Keyword(s):  
Sexual Dimorphism ◽  
Body Length ◽  
Sexual Size Dimorphism ◽  
Molecular Ecology ◽  
Female Size ◽  
Sexually Dimorphic ◽  
Size Dimorphism ◽  
Mating System Evolution ◽  
Accurate Comparison ◽  
Widespread Phenomenon

Sexual size dimorphism (SSD) describing intersexual size differences of a given taxon is a widespread phenomenon in the animal kingdom. SSD plays a significant role in understanding life history and mating system evolution. The snakelike morphology of limbless caecilian amphibians lacking obvious secondary sexual characters (in contrast to frogs and salamanders) impedes an accurate comparison between sexes.Here, the phylogenetically derived teresomatan and viviparous caecilianGeotrypetes seraphini seraphiniwas analysed for patterns of sexual dimorphism. In terms of body size females were the larger sex, but when body length was adjusted male-biased intersexual differences in cloacal shape appeared. The larger female size is likely explained by fecundity selection as clutch size was positively correlated to female body length. Unexpectedly a cryptic, ontogeny related variation of the nuchal collars was found. An overview of SSD in caecilians including data for 27 species of nine out of ten existing families revealed a quite high number of taxa showing sexually dimorphic head size dimensions exclusively present among phylogenetically derived teresomatan caecilians. Still further research including insights into the behavioural ecology and molecular ecology of mating systems is warranted to better understand the evolution of sexual size dimorphism of caecilian amphibians.

The evolution of sexual dimorphism in the lizard Anolis polylepis (Iguania): evidence from intraspecific variation in foraging behavior and diet

1996 ◽  
Vol 74 (7) ◽  
pp. 1238-1245 ◽  
Author(s):  
Gad Perry
Keyword(s):  
Sexual Selection ◽  
Sexual Dimorphism ◽  
Feeding Behavior ◽  
Rain Forest ◽  
Sexual Size Dimorphism ◽  
Costa Rican ◽  
Agonistic Interactions ◽  
Size Dimorphism ◽  
Food Items ◽  
Competing Hypotheses

Two main explanations, intraspecific niche divergence and sexual selection, have been proposed to explain the origin of sexual size dimorphism. To test these competing hypotheses I studied the ecology, feeding behavior, and diet of the lizard Anolis polylepis in a Costa Rican rain forest. Male A. polylepis were significantly larger and heavier than females but ate smaller food items and had lower stomach volumes, despite possessing longer and wider heads. Males were more sedentary than females or juveniles, chose higher perches, and were more likely to be involved in agonistic interactions. Diets of males, females, and juveniles were also significantly different taxonomically. These data are consistent with the sexual selection origin theory but not with an ecological one. Thus, observed dietary differences probably evolved once dimorphism had been attained through sexual selection.

Sexual Size Dimorphism: A Life History Perspective

Oikos ◽  
1989 ◽  
Vol 54 (2) ◽  
pp. 253 ◽  
Author(s):  
Jan Kozłowski ◽  
Jan Kozlowski
Keyword(s):  
Life History ◽  
Sexual Size Dimorphism ◽  
Size Dimorphism

scholarly journals Growth variability, dimensional scaling, and the interpretation of osteohistological growth data

2021 ◽  
Vol 17 (11) ◽  
Author(s):  
Thomas M. Cullen ◽  
Caleb M. Brown ◽  
Kentaro Chiba ◽  
Kirstin S. Brink ◽  
Peter J. Makovicky ◽  
...  
Keyword(s):  
Life History ◽  
Theoretical Models ◽  
Growth Patterns ◽  
Growth Data ◽  
Common Component ◽  
Growth Variability ◽  
Scaling Relationships ◽  
Dimensional Scaling ◽  
Taxonomic Description ◽  
History Of

Osteohistological data are commonly used to study the life history of extant and extinct tetrapods. While recent advances have permitted detailed reconstructions of growth patterns, physiology and other features using these data, they are most commonly used in assessments of ontogenetic stage and relative growth in extinct animals. These methods have seen widespread adoption in recent years, rapidly becoming a common component of the taxonomic description of new fossil taxa, but are often applied without close consideration of the sources of variation present or the dimensional scaling relationships that exist among different osteohistological measurements. Here, we use a combination of theoretical models and empirical data from a range of extant and extinct tetrapods to review sources of variability in common osteohistological measurements, their dimensional scaling relationships and the resulting interpretations that can be made from those data. In particular, we provide recommendations on the usage and interpretation of growth mark spacing/zonal thickness data, when these are likely to be unreliable, and under what conditions they can provide useful inferences for studies of growth and life history.

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