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.

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.

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.

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

Centrum growth patterns provide evidence for two small taxa of Hiodontidae in the Cretaceous Dinosaur Park Formation

2007 ◽  
Vol 44 (6) ◽  
pp. 721-732 ◽  
Author(s):  
Michael G Newbrey ◽  
Mark V.H Wilson ◽  
Allan C Ashworth
Keyword(s):  
Sexual Size Dimorphism ◽  
Growth Patterns ◽  
Growth Characteristics ◽  
Age And Growth ◽  
Mean Annual Temperature ◽  
Continuous Growth ◽  
Size Dimorphism ◽  
Extant Species ◽  
Multiple Species ◽  
Dinosaur Park Formation

Disarticulated centra recovered from the Campanian Dinosaur Park Formation (Cretaceous) are used to describe hiodontid age, growth, and longevity. Previous studies of Cretaceous centrum morphology have shown only one morphotype. However, growth characteristics can be used to test the one-taxon hypothesis. Age and growth characteristics indicate that Cretaceous hiodontids were shorter-lived (i.e., 7 years) and significantly smaller than extant Hiodon. The fossil centra also exhibit two significantly different growth patterns. Initially it was predicted that two factors could explain the presence of the two growth patterns: (1) sexual size dimorphism, and (2) variation in centrum size from multiple species. Sexual size dimorphism did not produce the two growth patterns because (1) H. alosoides maximum total length is significantly correlated with temperature, and (2) the paleotemperature in the depositional environment fluctuated approximately 6 °C mean annual temperature resulting in continuous growth variation. Concerning the second factor, the coefficient of variation (CV) observed in the Cretaceous centrum size data (0.23 CV) is 22% greater than that of the two extant species of Hiodon combined (0.18 CV) suggesting that at least two species of hiodontids were present in the Dinosaur Park Formation. The distribution of sizes of the smaller Cretaceous centra is not different from one extant species but is significantly different from two species suggesting that three taxa were not present.

scholarly journals Sexual size dimorphism in the Tyrrhenian tree frog: a life-history perspective

2011 ◽  
Vol 286 (4) ◽  
pp. 285-292 ◽  
Author(s):  
G. Cadeddu ◽  
C. Giacoma ◽  
S. Castellano
Keyword(s):  
Life History ◽  
Sexual Size Dimorphism ◽  
Tree Frog ◽  
Size Dimorphism

scholarly journals Degree of anisogamy is unrelated to the intensity of sexual selection

2021 ◽  
Vol 11 (1) ◽  
Author(s):  
Judit Mokos ◽  
István Scheuring ◽  
András Liker ◽  
Robert P. Freckleton ◽  
Tamás Székely
Keyword(s):  
Sex Differences ◽  
Sexual Selection ◽  
Life History ◽  
Parental Care ◽  
Sex Roles ◽  
Sexual Size Dimorphism ◽  
Ecological Factors ◽  
Size Dimorphism ◽  
Wide Range ◽  
Males And Females

AbstractMales and females often display different behaviours and, in the context of reproduction, these behaviours are labelled sex roles. The Darwin–Bateman paradigm argues that the root of these differences is anisogamy (i.e., differences in size and/or function of gametes between the sexes) that leads to biased sexual selection, and sex differences in parental care and body size. This evolutionary cascade, however, is contentious since some of the underpinning assumptions have been questioned. Here we investigate the relationships between anisogamy, sexual size dimorphism, sex difference in parental care and intensity of sexual selection using phylogenetic comparative analyses of 64 species from a wide range of animal taxa. The results question the first step of the Darwin–Bateman paradigm, as the extent of anisogamy does not appear to predict the intensity of sexual selection. The only significant predictor of sexual selection is the relative inputs of males and females into the care of offspring. We propose that ecological factors, life-history and demography have more substantial impacts on contemporary sex roles than the differences of gametic investments between the sexes.

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