Post settlement behaviour of brachiopods on hard and soft substrates

Richardson, J. Reginald; Aldridge, Anthony E.; Endersby, Ian

doi:10.1080/03014220709510062

Cited by 7 publications

(7 citation statements)

References 12 publications

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“…3B). The flume experiments do not indicate a preferential or hydrodynamically stable orientation relative to the direction of flow, but it certainly seems plausible that Morph B may have been more commonly aligned with the anterior-posterior axis perpendicular to flow, as has been observed with some modern brachiopods (LaBarbera 1977(LaBarbera , 1978Richardson et al 2007). However, unlike in modern brachiopods, without pedicle adjustor muscles the pedicle on atrypide brachiopods would not have been capable of reorientation/pivoting of the shell, and would have primarily served as an attachment point to the substrate (Copper 1966b(Copper , 1967Rudwick 1970).…”

Section: Discussionmentioning

confidence: 86%

Breaking the mold: using biomechanical experiments to assess the life orientation of dorsibiconvex brachiopods

Barclay¹,

Schneider²,

Leighton³

2015

Paleobiology

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Understanding the life orientation of fossil organisms, such as brachiopods, is not only important for understanding the biology of the organism in question, but it also can be used to interpret paleoecological information about the assemblages from which the specimens were derived. The dorsibiconvex brachiopod morphology is particularly common, especially among the Order Atrypida, yet there have been few independent, biomechanical studies to assess the life orientation of these brachiopods. In this study, we assess potential orientations of two end-member morphologies of a dorsibiconvex brachiopod, Pseudoatrypa lineata, from the Mid–Late Devonian of North America by placing realistic models in a flume.Using materials with the specific gravity of calcium carbonate, we modeled two well-preserved Pseudoatrypa lineata from the Waterways Formation (Givetian–Frasnian, Alberta, Canada) to represent the original shell. The hydrodynamic stability of the models was assessed by placing the models in a recirculating flume in one of three initial orientations: (1) anterior commissure upstream, (2) umbo upstream, and (3) lateral (specimen perpendicular to flow), each with the dorsal and ventral valve topmost. The entire process was conducted both on a Plexiglas substrate and on well-sorted, mediumgrained sand. All scenarios were repeated five times for a total of sixty trials per specimen (120 total).Flume trials indicate that neither brachiopod had a true hydrodynamically stable orientation.Reorientations occurred at low velocities (~0.2 m/s), with transport occurring soon after (~0.3 m/s).Assuming that a juvenile, pedunculate, dorsibiconvex brachiopod would initially have been oriented with its ventral valve topmost, our results suggest two outcomes: the brachiopods either (1) were attached via pedicles throughout their lives or (2) lived in quiet, undisturbed waters. Given the abundance of dorsibiconvex brachiopods in observed high-energy environments, our results indicate it is more conservative to assume dorsibiconvex brachiopods retained pedicles throughout their lives.

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Section: Discussionmentioning

confidence: 86%

Breaking the mold: using biomechanical experiments to assess the life orientation of dorsibiconvex brachiopods

Barclay¹,

Schneider²,

Leighton³

2015

Paleobiology

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“…Extant species can also live attached to larger rock outcrops (Richardson 1981b)-even the characteristically freelying Neothyris can occasionally be found attached to rock walls (Chapman and Richardson 1981). In the extant Magasella sanguinea, populations on unconsolidated substrates have greater shell convexity (Richardson et al 2007). Given that, the greater convexity typical FIGURE 13.…”

Section: Discussionmentioning

confidence: 99%

“…Although some extant brachiopods can occupy soft and even muddy sediments, in some cases attached to small shell fragments or rocks (Richardson and Watson 1975; Richardson 1981b; Stewart 1981; Richardson et al 2007), most living shallow-marine populations inhabit hard substrates, carbonate sediments, and areas of low to moderate sedimentation (Foster 1974; Noble et al 1976; Witman and Cooper 1983; Lee 1991; Kowalewski et al 2002). Brachiopods preferentially occur in such environments because hard and often cryptic attachment sites minimize the burrowing, grazing, and dislodging activity of other organisms (Witman and Cooper 1983; Tomašových 2008).…”

Section: Introductionmentioning

confidence: 99%

The role of bioturbation-driven substrate disturbance in the Mesozoic brachiopod decline

Manojlovic

Clapham

2020

Paleobiology

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Brachiopods dominated the seafloor as a primary member of the Paleozoic fauna. Despite the devastating effects of the end-Permian extinction, the group recovered during the early Mesozoic only to gradually decline from the Jurassic to today. This decline likely had multiple causes, including increased predation and bioturbation-driven substrate disruption, but the role of changing substrate is not well understood. Given the importance of substrate for extant brachiopod habitat, we documented Mesozoic–Cenozoic lithologic preferences and morphological changes to assess how decreasing firm-substrate habitat may have contributed to the brachiopod decline. Compared with bivalves, Mesozoic brachiopods occurred more frequently and were disproportionately abundant in carbonate lithologies. Although patterns in glauconitic or ferruginous sediments are equivocal, brachiopods became more abundant in coarser-grained carbonates and less abundant in fine-grained siliciclastics. During the Jurassic, brachiopod species rarely had abraded beaks but tended to be more convex with a high beak, potentially consistent with a non-analogue lifestyle resting on the seafloor. However, those highly convex morphotypes largely disappeared by the Cenozoic, when more terebratulides had abraded beaks, suggesting closer attachment to hard substrates. Rhynchonellides disproportionately declined to become a minor component of Cenozoic faunas, perhaps because of less pronounced morphological shifts. Trends in lithologic preferences and morphology are consistent with bioturbation-driven substrate disruption, with brachiopods initially using firmer carbonate sediments as refugia before adapting to live primarily attached to hard surfaces. This progressive habitat restriction likely played a role in the final brachiopod decline, as bioturbating ecosystem engineers transformed benthic habitats in the Mesozoic and Cenozoic.

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“…The increase of weight may have facilitated its stabilisation with a small and short inert pedicle, or even when the animal might have adopted a free-lying habit (a similar situation has been reported by Á lvarez and Emig 2005 for the morphologically similar terebratulinid Gryphus vitreus), a necessity on a seabed with reduced opportunities of fixation, such as those where the suitable substrate is mainly unconsolidated sediments (Curry 1981;Richardson 1981;Endo 1989). Overall, the morphology of Carneithyris subregularis thus suggests a specialised life habit on soft substrates (Richardson et al 2007). A secondary free-living habit, inferred in terebratulides displaying posteriorly thickened shells was described by Surlyk (1972).…”

Section: Palaeoecologymentioning

confidence: 92%

Taxonomy and palaeoecology of brachiopods from the South-Helvetic zone of the Fäneren region (Lutetian, Eocene, NE Switzerland)

Sulser

García‐Ramos

Kürsteiner³

et al. 2010

Swiss J Geosci

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Terebratuloid and cancellothyridoid brachiopods from the South-Helvetic Lutetian (Eocene) of the Fäneren region (NE Switzerland) are described: Carneithyris subregularis (QUENSTEDT) and two forms of Terebratulina s.l. under open nomenclature. Several species of Alpine and non-Alpine origin, related to Carneithyris subregularis, like Terebratula kickxi GALEOTTI, Terebratula aequivalvis SCHAFHÄ UTL and Terebratula hilarionis DAVID-SON show characters, which compare well with Carneithyris subregularis. Two of them, T. aequivalvis and T. hilarionis, are assigned to the genus Carneithyris. The stratigraphy and lithology of the sediments in the study area are reassessed. Life habits and palaeoecology of the brachiopods are discussed. C. subregularis apparently was a free living brachiopod without attachment to the substrate, as indicated by massive accumulations of callosities in the posterior parts of the shell. The variability of the cardinal process, as seen in the studied Carneithyris group can be interpreted as a morphological element to enlarge the surface of attachment of strong diductor muscles in relation to the internal thickening of the individual.

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Post settlement behaviour of brachiopods on hard and soft substrates

Cited by 7 publications

References 12 publications

Breaking the mold: using biomechanical experiments to assess the life orientation of dorsibiconvex brachiopods

Breaking the mold: using biomechanical experiments to assess the life orientation of dorsibiconvex brachiopods

The role of bioturbation-driven substrate disturbance in the Mesozoic brachiopod decline

Taxonomy and palaeoecology of brachiopods from the South-Helvetic zone of the Fäneren region (Lutetian, Eocene, NE Switzerland)

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