Sexual dimorphism and life history of Keichousaurus hui (Reptilia: Sauropterygia)

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.

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Life history of Tendaguru sauropods as inferred from long bone histology

Fossil Record ◽

10.1002/mmng.1999.4860020107 ◽

1999 ◽

Vol 2 (1) ◽

pp. 103-112 ◽

Cited By ~ 12

Author(s):

P. M. Sander

Keyword(s):

Life History ◽

Body Size ◽

Sexual Dimorphism ◽

Sexual Maturity ◽

Upper Jurassic ◽

Bone Histology ◽

Long Bone ◽

Large Mammals ◽

Growth Series ◽

History Of

Abstract. Sauropod dinosaurs present exceptional challenges in understanding their biology because of their exceptional body size. One of these, life history, can be inferred from the histology of their bones. For this purpose, the diverse sauropod assemblage of the Upper Jurassic Tendaguru beds was sampled with a new coring method which provided unprecented access to and insights into sauropod bone histology. Growth series of humeri and femora as well as long growth records from single bones suggest that all four sauropod taxa are characterized by continued growth after sexual maturity but that growth was determinate. Fibrolamellär bone is dominant in the samples, indicating that the bones of the Tendaguru sauropods grew at rates comparable to those of modern large mammals. The growth pattern of these sauropods thus combines typically reptilian traits with typically mammalian traits. In the details of their bone histology, the Tendaguru sauropod taxa show considerable variation which reflects life history. In addition, Barosaurus exhibits probable sexual dimorphism in bone histology. Das Verständnis der Biologie der sauropoden Dinosaurier wird durch ihre enorme Körpergröße außerordentlich erschwert. Allerdings kann ein Aspekt, die Lebensgeschichte, anhand der Histologie ihrer Knochen untersucht werden. Zu diesem Zweck wurde die diverse Sauropoden-Vergesellschaftung der oberjurassischen Tendaguru-Schichten beprobt, und zwar mit einer neuartigen Kernbohrmethode, die einen herausragenden Zugang und Einblick in die Knochenhistologie der Sauropoden ermöglichte. Wachstumsserien von Humeri und Femora sowie umfassende Überlieferungen des Wachstums von Individuen anhand einzelner Knochen machen es wahrscheinlich, daß alle vier Sauropoden-Taxa der Tendaguru-Schichten durch ein auch nach der Geschlechtsreife anhaltendes Wachstum gekennzeichnet waren. Allerdings ging das Wachstum nicht bis zum Tode des Tieres weiter, sondern kam bei einer etwas variablen Maximalgröße zum Stillstand. Fibrolamellärer Knochen ist der vorherrschende Knochentyp in den Proben, was anzeigt, daß die Tendaguru-Sauropoden mit für Säugetieren typische Raten wuchsen. Die Tendaguru-Sauropoden kombinerten also ein für Reptilien typisches Muster des Wachstums, nämlich nach der Geschlechtsreife anhaltendes Wachstum, mit für Säuger typischen Raten des Wachstums. Die verschiedenen Sauropoden-Taxa zeigen erstaunliche Unterschiede in den Details ihrer Knochenhistologie, die Unterschiede in der Lebensgeschichte belegen. Bei Barosaurus scheint außerdem ein Geschlechtsdimorphismus in der Histologie der Langknochen vorzukommen. doi:1002/mmng.1999.4860020107

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Sexual dimorphism, population dynamics and some aspects of life history of Echiniscus mauccii (Tardigrada; Heterotardigrada)

Journal of Limnology ◽

10.4081/jlimnol.2007.s1.126 ◽

2007 ◽

Vol 66 (1s) ◽

pp. 126 ◽

Cited By ~ 6

Author(s):

Colleen R. MITCHELL ◽

Frank A. ROMANO III

Keyword(s):

Population Dynamics ◽

Life History ◽

Sexual Dimorphism ◽

History Of

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Life in the trees: the ecology and life history of Kentropyx striatus (Teiidae) in the lavrado area of Roraima, Brazil, with comments on the life histories of tropical teiid lizards

Canadian Journal of Zoology ◽

10.1139/z92-270 ◽

1992 ◽

Vol 70 (10) ◽

pp. 1995-2006 ◽

Cited By ~ 25

Author(s):

Laurie J. Vitt ◽

Celso Morato de Carvalho

Keyword(s):

Life History ◽

Body Size ◽

Sexual Dimorphism ◽

Prey Size ◽

Annual Rainfall ◽

Activity Period ◽

Body Temperatures ◽

Wet Season ◽

Reproductive Characteristics ◽

History Of

The ecology and life history of the tropical teiid lizard Kentropyx striatus were studied in a grassland of northern Brazil, the lavrado area. The area, located nearly at the equator, experiences a prolonged dry season with a wet season extending from May to September. Total annual rainfall averages 1750 mm. Lizards were nonrandomly distributed among habitat patches and microhabitats. Most individuals were in trees and shrubs surrounding temporary and permanent water. Most individuals were observed active during late morning, the time period during which feeding and social interactions were observed. Lizards bask to achieve active body temperatures averaging 35.7 ± 0.23 °C. Body temperature is correlated with both substrate and air temperatures; foraging lizards maintained higher temperatures than basking lizards regardless of whether they were in sun, and lizards sampled when there was cloud cover had lower body temperatures than those sampled when sun was available. Females reach sexual maturity at 74 mm snout–vent length (SVL), produce 3–9 eggs per clutch, reproduce more than once per season, and commence reproduction during the wet season. Lizards hatch from eggs at 31 mm SVL. Maturity appears to be reached in 1 year or less. Overall, female reproductive characteristics are similar to those of other tropical teiid lizards that have been studied, with body size explaining much of the variance in reproductive characteristics across species. There is pronounced sexual dimorphism, with males larger in body size as well as certain other characteristics independent of body size. Sexual dimorphism appears to be a consequence of sexual selection. The diet is varied, but is dominated volumetrically by frogs, eruciform larvae, and spiders. Lizard body size accounted for only 5.5% of the variance in prey size and there was no difference in prey size due to sex. The occurrence of frogs and lizards in K. striatus stomachs suggests that teiid lizards may influence the structure of lizard and frog assemblages. The similarity of K. striatus to other studied tropical teiids in reproductive characteristics, morphology, activity period, activity temperatures, and diet underscore the conservative nature of the ecology of teiid lizards, presumably a consequence of their mode of prey acquisition.

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

Biology Letters ◽

10.1098/rsbl.2008.0409 ◽

2008 ◽

Vol 4 (6) ◽

pp. 719-723 ◽

Cited By ~ 42

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.

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