Brood care in a Silurian ostracod

Abstract

An exceptionally preserved new ostracod crustacean from the Silurian of Herefordshire, England, preserves eggs and possible juveniles within its carapace, providing an unequivocal and unique view of parental brood care in the invertebrate fossil record. The female fossil is assigned to a new family and superfamily of myodocopids based on its soft-part anatomy. It demonstrates a remarkably conserved egg-brooding reproductive strategy within these ostracods over 425 Myr. The soft-tissue anatomy urges extreme caution in classifying 'straight-hinged' Palaeozoic ostracods based on the carapace alone and fundamentally questions the nature of the shell-based Palaeozoic ostracod record.

A Silurian myodocope with preserved soft-parts: cautioning the interpretation of the shell-based ostracod record

“…This confirms that carapace morphology alone is an inadequate basis for suprageneric assignment of (Recent) myodocopes [41]. The discovery of P. avibella with a soft-part morphology that is at odds with the appearance of the carapace encourages caution in interpreting the affinities of Palaeozoic ostracods based merely on shell morphology [1,19,20]. The current taxonomic assignment of many fossil ostracods, especially Palaeozoic forms, may be flawed.…”

“…A marked adductorial sulcus and prominent lobation are features typical of Palaeocopida [39], the diverse and abundant Palaeozoic ostracod group that is known from carapaces alone and comprises some 500 genera (D. J. Siveter 2008, unpublished data), although the majority of palaeocopes characteristically have an adventral structure(s), which is lacking in P. avibella. P. avibella and the three other known Palaeozoic myodocope species with soft-parts, Nymphatelina gravida, Nasunaris inflata and Colymbosathon ecplecticos (figure 2a, k-m; [18][19][20]), show a diversity of carapace morphologies even though their soft-parts indicate that all four are myodocopids and all but Nymphatelina are cylindroleberidids (these assignments receive independent support from molecular/morphological analysis of fossil and Recent ostracods [40]). This confirms that carapace morphology alone is an inadequate basis for suprageneric assignment of (Recent) myodocopes [41].…”

“…The soft-parts of ostracods are rarely fossilized [13,14]. From the Palaeozoic a single ostracod-type limb is known from the Late Cambrian [15]; a podocopid specimen with some soft-parts [16] and an undescribed, partially open carapace with poorly preserved limbs [17] from the Devonian; and three myodocope species, each based on an essentially completely preserved specimen, from the Herefordshire (Silurian) Konservat-Lagerstätte, UK [18][19][20]. Here, we describe a new ostracod with soft-parts from the Herefordshire deposit, Pauline avibella gen. et sp.…”

The operculum of Otostoma Retzii (Nilsson, 1827) (Gastropoda, Neritidae; Late Cretaceous) and its phylogenetic significance

“…Under a variety of unusual taphonomic circumstances, however, they may be preserved, even in strata as ancient as Precambrian (see e.g., Xiao et al 1998;Knoll 1999, 2000). Most invertebrate eggs de− scribed from the fossil record, whether isolated from or in asso− ciation with their producers, belong to arthropods (Briggs and Clarkson 1985;Siveter et al 2007;Shen and Huang 2008;Huang et al 2008). Molluscan eggs are much rarer, particularly those of gastropods, as was recently pointed out by Zatoń et al (2009).…”

Three-Dimensionally Preserved Decapod Larval Compound Eyes from the Cretaceous Santana Formation of Brazil

“…Recently, Vannier et al (2009) also mentioned a two-dimensionally preserved compound eye with eyestalks in the arthropod Isoxys from the Lower Cambrian Maotianshan Shale of Yunnan Province, China and from the Burgess Shale. Siveter et al (2003Siveter et al ( , 2007 described lateral, presumed compound eyes from two myodocope genera, Colymbosatton and Nymphatelina, from the Silurian of Herefordshire, U.K. In Recent Malacostraca, stalked eyes are ubiquitous among decapods, and their morphology and function have been well studied (e.g., Land, 1981;Nilsson, 1989;Warrant and McIntyre, 1992;MeyerRochow, 2001).…”