A Lower Cambrian vertebrates from South China

Nature (Impact Factor: 41.46). 11/1999; 402(6757):42-46. DOI: 10.1038/46965


The first fossil chordates are found in deposits from the Cambrian
period (545-490 million years ago), but their earliest record is
exceptionally sporadic and is often controversial. Accordingly, it has
been difficult to construct a coherent phylogenetic synthesis for the
basal chordates. Until now, the available soft-bodied remains have
consisted almost entirely of cephalochordate-like animals from Burgess
Shale-type faunas. Definite examples of agnathan fish do not occur until
the Lower Ordovician (~475Myr BP), with a more questionable record
extending into the Cambrian. The discovery of two distinct types of
agnathan from the Lower Cambrian Chengjiang fossil-Lagerstätte is,
therefore, a very significant extension of their range. One form is
lamprey-like, whereas the other is closer to the more primitive hagfish.
These finds imply that the first agnathans may have evolved in the
earliest Cambrian, with the chordates arising from more primitive
deuterostomes in Ediacaran times (latest Neoproterozoic, ~555Myr BP), if
not earlier.

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    • "Living fossil lineages are particularly well represented among among non-tetrapod vertebrates, or ''fishes'' (Nelson, 2006), a fact that is not terribly surprising when viewed in the context of their deep-time evolutionary history and current species diversity. Fossils identifiable as ''fishes'' date to the Cambrian (Shu et al., 1999, 2003) and extant species diversity of ray-finned fishes represent approximately half of the planet's current vertebrate species diversity (Stiassny et al., 2004). With such a long time span in which to diversify and the great extent to which they have done so, chance alone would dictate that many present day fish species should represent the remnants of formerly species-rich radiations (Stanley, 1979). "
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    • "The latter has 20–30 pairs of gonads that can yield 30,000 low-yolky eggs ca 90–150 μm per year (Song and Xu, 1989; Yasui and Kubokawa, 2005). Both Haikouella and Yunnanozoon, as well as the earliest putative vertebrate Haikouichthys ercaicunensis Luo, Hu & Shu (Shu et al., 1999a), similarly have two strings of glands comparable in size and number with those of Amphioxus , and thus they possibly shed a large amount of small eggs per unit time; this case could then account for the fossil concentrations of numerous individuals of Haikouella/Yunnanozoon on the same bedding plane – the result of rapid burial in the Chengjiang deposits (Han et al., 2006). The apparent great fecundity of these animals would inevitably have triggered more intense competition among the members of the Chengjiang fauna, and this is consistent with the unfolding of the three discussed main extreme directions of animal development during "
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    ABSTRACT: The bivalved bradoriid arthropod Kunmingella douvillei (Mansuy, 1912) is the most common species in the Lower Cambrian Chengjiang Lagerstatte. Its soft anatomy has been reported based on well-preserved specimens. However, as with other Cambrian arthropods, its reproductive behavior is poorly documented. Rare specimens of K. douvillei preserved with eggs have been reported. Our new collections confirm that the eggs were directly attached to the last three pairs of biramous appendages and verify the head-trunk boundary suggested by previous work. The brooding behavior of K. douvillei was most probably related to its small body size, as in living crustaceans. The K. douvillei female could carry 50-80 eggs ranging from 150-180 mu m in diameter, possibly indicating a K-reproductive strategy; its ontogenetic and reproductive mode might have been an adaptation in response to increasing predatory pressure across the Ediacaran-Cambrian boundary. All of the three main directions of development in the life history of living marine invertebrates, namely planktotrophic larvae, lecithotrophic larvae, and brood care, most likely evolved by Stage 3 of the Cambrian.
    Gondwana Research 04/2014; 25(3):983–990. DOI:10.1016/ · 8.24 Impact Factor
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    • "Lampreys are jawless vertebrates that diverged from jawed vertebrates 560 million years ago (Kumar and Hedges, 1998; Shu et al., 1999). The sea lamprey life cycle consists of larval, parasitic juvenile and anadromous adult stages (Applegate, 1950; Hardisty, 1979; Hardisty and Potter, 1971). "
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    ABSTRACT: Secondary sexual characters in animals are exaggerated ornaments or weapons for intrasexual competition. Unexpectedly, we found that a male secondary sexual character in sea lamprey (Petromyzon marinus) is a thermogenic adipose tissue that instantly increases its heat production during sexual encounters. This secondary sexual character, developed in front of the anterior dorsal fin of mature males, is a swollen dorsal ridge known as the 'rope' tissue. It contains nerve bundles, multivacuolar adipocytes and interstitial cells packed with small lipid droplets and mitochondria with dense and highly organized cristae. The fatty acid composition of the rope tissue is rich in unsaturated fatty acids. The cytochrome c oxidase activity is high but the ATP concentration is very low in the mitochondria of the rope tissue compared with those of the gill and muscle tissues. The rope tissue temperature immediately rose up to 0.3°C when the male encountered a conspecific. Mature males generated more heat in the rope and muscle tissues when presented with a mature female than when presented with a male (paired t-test, P<0.05). On average, the rope generated 0.027±0.013 W cm(-3) more heat than the muscle in 10 min. Transcriptome analyses revealed that genes involved in fat cell differentiation are upregulated whereas those involved in oxidative-phosphorylation-coupled ATP synthesis are downregulated in the rope tissue compared with the gill and muscle tissues. Sexually mature male sea lamprey possess the only known thermogenic secondary sexual character that shows differential heat generation toward individual conspecifics.
    Journal of Experimental Biology 07/2013; 216(Pt 14):2702-2712. DOI:10.1242/jeb.085746 · 2.90 Impact Factor
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