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Journal ArticleDOI

Translating taxonomy into the evolution of conodont feeding ecology

01 Apr 2016-Geology (Geological Society of America)-Vol. 44, Iss: 4, pp 247-250
TL;DR: This study shows that the evolution of the platform in Polygnathus occurred to accommodate and dissipate the stress accumulation derived from the tooth-like function that the P 1 elements performed, suggesting that this recurrent motif of conodont evolution represents an adaptive response to recurrent functional selective pressures.
Abstract: Conodont research has long been divided between utilitarian applications to solve geological problems versus analysis of their paleobiology. However, recent advances in conodont functional analysis allow these independent stands of research to be unified, decoding the functional implications of their morphological variation. We demonstrate this using synchrotron tomography and finite element analysis, informed by occlusal and microwear analyses, to analyze functionally the classic evolutionary sequence of the genus Polygnathus. Our study shows that the evolution of the platform in Polygnathus occurred to accommodate and dissipate the stress accumulation derived from the tooth-like function that the P 1 elements performed, suggesting that this recurrent motif of conodont evolution represents an adaptive response to recurrent functional selective pressures. Our study establishes a framework in which the functional ecology of conodonts can be read from their rich taxonomy and phylogeny, representing an important attempt to understand the role of this abundant and diverse clade in the Phanerozoic marine ecosystems.

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Citations
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Journal ArticleDOI
TL;DR: Hindeodus parvus as mentioned in this paper was found to possess a raptorial array of two M and nine S elements (unpaired S 0; symmetrically paired S 1, S 2, S 3, S 4, S 5, S 6, S 7, S 8, S 9, S 10).
Abstract: Knowledge of the conodont skeleton, in terms of the morphology of the elements and the positions they occupy, provides the foundation for understanding of homology, taxonomy and evolutionary relationships in conodonts. This knowledge also underpins analyses of conodont functional morphology and feeding. Direct evidence of skeletal anatomy and apparatus architecture comes from natural assemblages: fossils that preserve together the articulated remains of the conodont apparatus, either collapsed onto a bedding plane or as clusters of elements in which juxtaposed and overlapping elements have been fused together by diagenetic minerals. Here we describe six clusters of the biostratigraphically important conodont Hindeodus parvus from the Lower Triassic Shangsi section, Sichuan Province, South China. Five of these clusters represent the partial remains of articulated skeletons, providing direct evidence of the number and arrangement of elements in the apparatus. Combined with data from previously published natural assemblages this provides a test of the hypothesis that Triassic conodonts had a reduced dentition. Hindeodus parvus possessed a complete raptorial array of two M and nine S elements (unpaired S0; symmetrically paired S1, S2, S3, S4); the paired P1 locations were occupied by carminiscaphate elements, but the apparatus lacked P2 elements. This is consistent with broader evidence for a particularly high degree of integration and constraint operating on the S–M array of morphologically complex conodonts, leading to conserved architecture of the array over a period of more than 250 million years. The loss of elements from the P domain implies a change in food processing ability and, given the predominance of data from P elements in conodont taxonomy and biostratigraphy, the hypothesis of element loss from the P domain has significant implications for the broader understanding of conodont diversity and evolutionary patterns.

17 citations

Journal ArticleDOI
TL;DR: In this article, high precision (TIMS double spike) stable isotope measurements of both δ 44/40 Ca and δ 88/86 Sr together with radiogenic 87 Sr/ 86 Sr ratios determined from conodont apatite were presented.

14 citations

Journal ArticleDOI
TL;DR: In this paper, the skeleton of a conodonts from the Middle Triassic Luoping Biota, Yunnan Province, Southwest China was analyzed using synchrotron radiation X-ray tomographic microscopy (SRXTM).

13 citations

Journal ArticleDOI
TL;DR: In this paper, the conodonts studied come from the latest Famennian-Tournaisian interval of the Kamenka River section (Timan-Pechora Basin).
Abstract: The δCorg values and their variations in conodont elements of the latest Famennian–Tournaisian species Polygnathus parapetus Druce are considered. The conodonts studied come from the latest Famennian–Tournaisian interval of the Kamenka River section (Timan-Pechora Basin). The carbon isotope composition of conodont elements had an average value of –25.2‰, suggesting a low trophic level of this species. During the latest Famennian (praesulcata conodont Zone) δCorg shifted to more negative values (up to –30.4‰), which may be attributed to changes in the global carbon cycle and local influx of organic matter of terrestrial origin during the terminal Famennian regression.

11 citations


Cites background from "Translating taxonomy into the evolu..."

  • ...These studies demonstrate that P1 elements of ozarkodinid conodonts, including the genus Polygnathus, are acting as occluding pairs (Nicoll 1987; Purnell & von Bitter 1992; Donoghue & Purnell 1999; Martínez-Pérez et al. 2016)....

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References
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Book
13 Oct 1988
TL;DR: Introduction Skeletal anatomy Whole animal anatomy Taxonomy The major conodont groups Paleoecology The phylum Conodonta Evolutionary patterns Appendixes Index
Abstract: Introduction Skeletal anatomy Whole animal anatomy Taxonomy The major conodont groups Paleoecology The phylum Conodonta Evolutionary patterns Appendixes Index

401 citations

Journal ArticleDOI
TL;DR: This study demonstrates that the relative performance of un-validated models can be compared so long as they are scaled properly, and offers a theoretical framework and empirical data demonstrating that scaling finite element models to equal force: surface area ratios removes the effects of model size and provides a comparison of stress-strength performance based solely on shape.

253 citations


"Translating taxonomy into the evolu..." refers methods in this paper

  • ...…per surface area scaling (Table DR1 in the GSA Data Repository1), meaning that we applied a functional load proportional in magnitude to surface area, therefore removing the effects of model size and providing a comparison of stress-strength performance based solely on shape (Dumont et al., 2009)....

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01 Jan 1994

55 citations


"Translating taxonomy into the evolu..." refers background or methods in this paper

  • ...Polygnathus underwent a dramatic diversification in the Emsian, characterized by increasing the platform size, changes in the oral surface of the platform, and the inversion of the basal cavity (Yolkin et al., 1994)....

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  • ...…platforms coincides with the cross sections of adult forms that have been used to characterize the early evolution of Polygnathus through the Pragian–Emsian, i.e., P. pireneae, P. kitabicus, P. excavatus, P. gronbergi, P. nothoperbonus, and P. inversus (Yolkin et al., 1994, their figure 2) (Fig....

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  • ...The increase in platform size occurred gradually, both through ontogeny and phylogeny, followed by more subtle changes in oral morphology and in the basal cavity configuration (Yolkin et al., 1994; Mawson, 1998)....

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  • ...The species are considered in the order of their position within the phylogeny of Polygnathus presented by Yolkin et al. (1994), from primitive to derived....

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Journal Article
TL;DR: Analysis of pairs of conodont elements from individuals of Idiognathodus indicates that these elements crushed food by rotational closure, which brought the oral surfaces into complex interpenetrative occlusion.
Abstract: Conodont element function and feeding mechanisms are of considerable paleobiological importance, yet many details remain poorly understood and speculative. Analysis based on mor- phology, physical juxtaposition, and patterns of surface damage and microwear on pairs of Pa el- ements from individuals of Idiognathodus indicates that these elements crushed food by rotational closure, which brought the oral surfaces into complex interpenetrative occlusion. Other molariform conodont elements also functioned in this manner. Occlusion of this complexity is unique among nonmammalian vertebrates, and is all the more surprising given that conodonts lacked jaws. In addition to enhanced understanding of food processing in conodonts, our analysis suggests that many details of conodont Pa element morphology, which underpin taxonomy and biostratigraphy, can now be interpreted in a paleobiological, functional context.

55 citations


"Translating taxonomy into the evolu..." refers methods in this paper

  • ...This model is compatible with the general model originally described by Donoghue and Purnell (1999)....

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Journal ArticleDOI
TL;DR: This work shows that the morphology of conodont food-processing elements was adapted to overcome size limitations through developing dental tools of unparalleled sharpness that maximize applied pressure.
Abstract: Conodonts have been considered the earliest skeletonizing vertebrates and their mineralized feeding apparatus interpreted as having performed a tooth function. However, the absence of jaws in conodonts and the small size of their oropharyngeal musculature limits the force available for fracturing food items, presenting a challenge to this interpretation. We address this issue quantitatively using engineering approaches previously applied to mammalian dentitions. We show that the morphology of conodont food-processing elements was adapted to overcome size limitations through developing dental tools of unparalleled sharpness that maximize applied pressure. Combined with observations of wear, we also show how this morphology was employed, demonstrating how Wurmiella excavata used rotational kinematics similar to other conodonts, suggesting that this occlusal style is typical for the clade. Our work places conodont elements within a broader dental framework, providing a phylogenetically independent system for examining convergence and scaling in dental tools.

51 citations


"Translating taxonomy into the evolu..." refers methods in this paper

  • ...Microwear analysis, computed tomography, and finite element analysis can now be combined to interpret conodont taxonomy, stratigraphy, and phylogeny in terms of feeding ecology (Jones et al., 2012; Martínez-Pérez et al., 2014a)....

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  • ...The occlusal cycle of Polygnathus is comparable to the rotation cycle described for Gnathodus bilineatus (Martínez-Pérez et al., 2014a) and Wurmiella (Jones et al., 2012), which also show evidence of episodic separation of the opposed elements as part of the occlusal cycle....

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