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1.
LENNART JEPPSSON 《Lethaia: An International Journal of Palaeontology and Stratigraphy》1971,4(1):101-123
The criteria used for logical and numerical reconstruction of conodont apparatuses are: (1) Similar stratigraphical and geographical occurrence. (2) Similar frequency variation. (3) Similar appearance of details in the conodont-elements. (4) Similar composition of the conodont apparatuses.
The position of conodont-elements in some types of apparatuses, as reconstructed by Lange (1968), is supported by further evidence, and it is also possible to reconstruct the precise position of certain elements. It is probable that a great number of apparatuses with compound conodont elements consisted of homologous elements and that a reconstruction of the positions of the elements from cluster material can be generalized to include all these apparatuses. From the periphery inwards, a complete apparatus of this type consisted of ne, hi, hi, pl, and tr elements and, posterior to these, of pairs of oz and sp elements. 相似文献
The position of conodont-elements in some types of apparatuses, as reconstructed by Lange (1968), is supported by further evidence, and it is also possible to reconstruct the precise position of certain elements. It is probable that a great number of apparatuses with compound conodont elements consisted of homologous elements and that a reconstruction of the positions of the elements from cluster material can be generalized to include all these apparatuses. From the periphery inwards, a complete apparatus of this type consisted of ne, hi, hi, pl, and tr elements and, posterior to these, of pairs of oz and sp elements. 相似文献
2.
The structure and evolution of Ordovician conodont apparatuses 总被引:1,自引:0,他引:1
CHRISTOPHER R. BARNES DAVID J. KENNEDY ALEXANDER D. McCRACKEN GODFREY S. NOWLAN GLEN A. TARRANT 《Lethaia: An International Journal of Palaeontology and Stratigraphy》1979,12(2):125-151
Multielement taxonomy was instituted for Ordovician conodonts over a decade ago, and probably a majority of the multielement genera have been defined or are well understood. The present systems of notation for elements within apparatuses are inadequate and cumbersome. A new notation scheme is proposed which applies a single-letter code to the position in the apparatus occupied by certain element morphotypes. The taxonomic status of all known Ordovician conodont genera is reviewed (appendix) using the new notation, and a new scheme to classify conodont apparatuses is presented. Five main apparatus types (I-V) and seventeen subtypes (IA-IC, etc.) are defined. Within these groups, all known Ordovician conodont genera can be accommodated, and probably few new groups are required to include all other conodont genera. The apparatus types and subtypes are defined on the basis of symmetry, curvature, and number of the element types, with a clear distinction being made between the first and second transition series. Certain homologous relationships, both between and within many apparatus types, are noted. The evolution of the five major types, and the subtypes, is traced through the Ordovician. The pattern of evolution suggests that the types and subtypes recognized are probably natural biologic groupings, largely reflecting phylogenetic change. 相似文献
3.
Conodont element function 总被引:1,自引:0,他引:1
LENNART JEPPSSON 《Lethaia: An International Journal of Palaeontology and Stratigraphy》1979,12(2):153-170
There are close similarities between conodont elements and teeth both in general shape and in that they possess pointed tips and have expanded bases with more porous tissue. A number of examples of conodont elements which parallel specific kinds of tooth shapes and organizations are added to earlier known similarities. Both in teeth and in conodont elements the surface structures include cutting edges, striations, and barbs. The change in strength of the conodont denticles caused by the evolution of white matter is also shown to agree with a tooth function. On the other hand, the elements grew throughout the life of the animal by lamellae added to the surface. The solution of this paradox is found in the elements alternating between a growth phase and a functional phase. During growth the oral surface of the elements was enveloped in folds of secreting soft tissue. Structures henceforth termed burrs were formed at the contacts between the folds. Parts of the burrs evolved into cutting edges. Three different bite types occurred among the conodont elements. Many (all?) conodonts were predators which used their elements to seize and to process the food mechanically. The shape of the conodont elements cannot be used for conclusions regarding the affinities of the conodonts. Similarly, an identification of a fossil as belonging to the conodonts must be supported by other evidence than just shape. 相似文献
4.
Conopiscius shares V-shaped myomeres with the co-occurring conodont Clydagnathus but instead of a complex oral apparatus it has only a single pair of conical elements, and structures resembling scales are associated with its myomeres. Moreover, the coarsely crystalline crown tissue typical for conodonts has not been identified in the Conopiscius elements, which show only a finely lamellar skeletal tissue. The gap between conodonts and Conopiscius may be filled by isolated elements of similar morphology and structure occurring in the Late Devonian. They reveal a very thin external layer developed mostly at the tooth tip and resembling conodont crown tissue. The pulp cavity is partially filled with layered or spherulitic phosphatic tissue of the kind known also in conodonts (basal filling tissue) and early vertebrates (lamellin). Conodont elements of similar morphology and representing uni-membrate oral apparatuses have not been previously reported from the Devonian or Carboniferous but occur near the Cambrian–Ordovician transition ( Proconodontus ) and in the Late Permian ( Caenodontus ). It is proposed that Conopiscius represents a mostly cryptic conodont lineage extending from the Early Ordovician to the Permian, instead of being directly related to the agnathans. 相似文献
5.
Duncan J. E. Murdock Ivan J. Sansom Philip C. J. Donoghue 《Proceedings. Biological sciences / The Royal Society》2013,280(1768)
The morphological disparity of conodont elements rivals the dentition of all other vertebrates, yet relatively little is known about their functional diversity. Nevertheless, conodonts are an invaluable resource for testing the generality of functional principles derived from vertebrate teeth, and for exploring convergence in a range of food-processing structures. In a few derived conodont taxa, occlusal patterns have been used to derive functional models. However, conodont elements commonly and primitively exhibit comparatively simple coniform morphologies, functional analysis of which has not progressed much beyond speculation based on analogy. We have generated high-resolution tomographic data for each morphotype of the coniform conodont Panderodus acostatus. Using virtual cross sections, it has been possible to characterize changes in physical properties associated with individual element morphology. Subtle changes in cross-sectional profile have profound implications for the functional performance of individual elements and the apparatus as a whole. This study has implications beyond the ecology of a single conodont taxon. It provides a basis for reinterpreting coniform conodont taxonomy (which is based heavily on cross-sectional profiles), in terms of functional performance and ecology, shedding new light on the conodont fossil record. This technique can also be applied to more derived conodont morphologies, as well as analogous dentitions in other vertebrates and invertebrates. 相似文献
6.
RICHARD J. KREJSA PABLO BRINGAS JR. HAROLD C. SLAVKIN 《Lethaia: An International Journal of Palaeontology and Stratigraphy》1990,23(4):359-378
Krejsa, R. J., Bringas, P. Jr. & Slavkin, H. C. 1990 10 15: A neontological interpretation of conodont elements based on agnathan cyclostome tooth structure, function, and development. Lethaia , Vol. 23, pp. 359–378. Oslo. ISSN 0024–1164.
Speculation about a conodont-cyclostome connection has led us to search for and establish a biological basis for various characteristic structures in conodont elements. Measurements of juvenile hagfish palatal and lingual teeth overlap those of representative conodont elements, demonstrating a size correspondence of conodonts with teeth of living vertebrates. When hagfish tooth histology is compared with internal and surface topography (SEM) of hagfish, keratinous teeth and mineralized conodont elements, microspaces and tubules similar to those found in hagfish functional tooth coverings and replacement elements are also found within the white matter' of conodont elements. It is provisionally suggested that the primary organic matrix of conodont elements could be keratin and/or keratin-related molecules, and that individual conodont elements could represent shed tooth coverings. The basal bodies' found in certain conodont elements could be replacement elements. These interpretations are contrary to several paradigms of orthodox conodontology. ▭ Agnatha, conodonts, cyclostomes, hagfish, keratin, paleo-biology, shedding, teeth . 相似文献
Speculation about a conodont-cyclostome connection has led us to search for and establish a biological basis for various characteristic structures in conodont elements. Measurements of juvenile hagfish palatal and lingual teeth overlap those of representative conodont elements, demonstrating a size correspondence of conodonts with teeth of living vertebrates. When hagfish tooth histology is compared with internal and surface topography (SEM) of hagfish, keratinous teeth and mineralized conodont elements, microspaces and tubules similar to those found in hagfish functional tooth coverings and replacement elements are also found within the white matter' of conodont elements. It is provisionally suggested that the primary organic matrix of conodont elements could be keratin and/or keratin-related molecules, and that individual conodont elements could represent shed tooth coverings. The basal bodies' found in certain conodont elements could be replacement elements. These interpretations are contrary to several paradigms of orthodox conodontology. ▭ Agnatha, conodonts, cyclostomes, hagfish, keratin, paleo-biology, shedding, teeth . 相似文献
7.
P. C. J. Donoghue 《Philosophical transactions of the Royal Society of London. Series B, Biological sciences》1998,353(1368):633
Recent advances in our understanding of conodont palaeobiology and functional morphology have rendered established hypotheses of element growth untenable. In order to address this problem, hard tissue histology is reviewed paying particular attention to the relationships during growth of the component hard tissues comprising conodont elements, and ignoring a priori assumptions of the homologies of these tissues. Conodont element growth is considered further in terms of the pattern of formation, of which four distinct types are described, all possibly derived from a primitive condition after heterochronic changes in the timing of various developmental stages. It is hoped that this may provide further means of unravelling conodont phylogeny. The manner in which the tissues grew is considered homologous with other vertebrate hard tissues, and the elements appear to have grown in a way similar to the growing scales and growing dentition of other vertebrates. 相似文献
8.
NICOLAS GOUDEMAND MICHAEL J. ORCHARD PAUL TAFFOREAU SEVERINE URDY THOMAS BRÜHWILER ARNAUD BRAYARD THOMAS GALFETTI HUGO BUCHER 《Palaeontology》2012,55(5):1021-1034
Abstract: Several fused clusters of conodont elements of the genera Neospathodus and Novispathodus were recovered from limestone beds at the Dienerian–Smithian and Smithian–Spathian boundaries, respectively, from several localities in Guangxi province, South China. Conodont clusters are otherwise extremely rare in the Triassic, and these are first described for the Early Triassic. The exceptional specimens partially preserve the relative three‐dimensional position and orientation of ramiform elements and are therefore extremely important for testing hypotheses on the architecture of apparatuses. These specimens partly confirm the previous reconstruction of the Novispathodus apparatus by Orchard. Within apparatuses of members of superfamily Gondolelloidea, elements previously identified as occupying the S1 and S2 positions instead occupy the S2 and S1 positions. Similarly, within apparatuses of members of the subfamily Novispathodinae, elements previously referred to S3 and S4 positions are reinterpreted to have occupied S4 and S3 positions, respectively. 相似文献
9.
CARL B. REXROAD THOMAS L. THOMPSON 《Lethaia: An International Journal of Palaeontology and Stratigraphy》1979,12(3):235-243
Evolutionary lineages of conodont elements and of some apparatuses are gradually being documented to increase the value of these fossils in stratigraphic interpretation and to further our understanding of conodont taxonomy. The well-documented faunas from Mississippian strata of the Illinois Basin and type Mississippian beds provide a great deal of information for the recognition of phylogenies. The disjunct element genus Spathognathodus is part of a basic and long-ranging type of conodont apparatus from which a number of other forms have been derived, and some of its Mississippian disjunct element species can now be placed in multielement species. A lineage involving spathognathodont Pa elements recognized in the Mississippian, then, is the basis of the present study. The phylogeny recognized started with Synprioniodina? crassidentata, and includes S.? regularis, S.? pulchra, S.? coalescens, S.? spicula, Hinduodus cristula, and H. minutus in the Mississippian. Aputiignathus scitulus and A. penrscitulus apparently represent a separate line, which also might include disjunct element Spathognathodus rexroadi. 相似文献
10.
The Early Triassic is a critical interval for the study of recovery from the terminal Permian mass extinction, as there are small-scale extinction events, which may have contributed to the delayed recovery. The systematic measuring and sampling of a 12-m-thick section at the Mokrice locality in eastern Slovenia has resulted in the recovery of a conodont fauna from the Olenekian beds. Four conodont zones have been recognized. These zones are in ascending order as follows: the Hadrodontina aequabilis Zone, Platyvillosus corniger Zone, Platyvillosus regularis Zone, and Triassospathodus hungaricus Zone. These conodont zones confirm the proposed conodont biozonation sequence in western Slovenia and have correlation value especially for the western marginal Tethys. Multielement conodont apparatuses of Triassospathodus hungaricus and Platyvillosus regularis have been reconstructed based on conodont elements that were recently obtained from the Slovenian sections. Although the S2element was not found, the apparatus indicates that the conodont species “Spathognathodus” hungaricus should be assigned to the genus Triassospathodus. 相似文献
11.
Andrey V. Zhuravlev 《Lethaia: An International Journal of Palaeontology and Stratigraphy》2001,34(2):136-142
The elements of many conodont taxa exhibit a polygonal surface micro-ornamentation. Four main types are recognized (striation, linear texture, regular (idiomorphic) texture and granular texture) and their distribution over the conodont elements of different morphology is considered. The intraspecific (ontogenetic and ecological) and interspecific (phylogenetic) causes of the reticulation texture variations are also considered. 相似文献
12.
《Palaeoworld》2019,28(4):429-440
The composition of conodont apparatuses is crucial for understanding the feeding mechanisms of these early vertebrates. However, the multielement apparatus reconstructions of most species remain equivocal because they have been inferred from loose element collections, guided by knowledge from rare articulated ‘bedding plane assemblages’ and fused clusters, often from distantly related taxa. Even these natural assemblages can be difficult to interpret because the component elements can be closely juxtaposed or embedded in matrix, making it hard to discern the morphology of each element and their relative positions within the architecture of the feeding apparatus. Here we report five exceptionally preserved conodont clusters from the Middle Triassic Luoping Biota, Yunnan Province, Southwest China. These materials were scanned using synchrotron radiation X-ray tomographic microscopy (SRXTM), revealing the morphology and positional homology of the component elements in the fused clusters. We confirm that the apparatus of Nicoraella was composed of eight types of elements, comprising a total of 15 elements. SRXTM reveals the positional homologies of the component elements, viz. a single alate element is located in the S0 position, flanked successively abaxially by pairs of breviform digyrate S1 and S2 elements, bipennate S3 and S4 elements, and a pair of inwardly curved breviform digyrate M elements. Carminate elements occupy the P1 and P2 positions. The apparatus of Nicoraella is among the most completely characterised of all conodonts and serves as a template for the reconstruction of gondollellids. 相似文献
13.
HAZEL JANE McGOFF 《Lethaia: An International Journal of Palaeontology and Stratigraphy》1991,24(3):235-247
Accurate palacobiological interpretation of the fossil record requires an assessment of biostratinomic processes. Samples which have undergone significant post-mortem sorting reflect only the hydrodynamic regime prevalent at the time of deposition and not the original faunal composition. Conodont bedding plane assemblagcs are rare and many conodont taxa are known only through reconstructions of apparatuses using empirical techniques. These methods require large collections where the elements have undergone no significant post-mortem transportation. In this paper measurements of settling velocities are used to predict relative hydrodynamic behaviour in a current. The settling velocity of a particle is of about the same magnitude as the current required to entrain that particle. Conodont elements rotate during fall, spinning about a central axis. Elements with equal Reynolds numbers may have different drag coefficients indicating that shape is an important factor in determining conodont element hydrodynamics. In a current of increasing velocity the predicted order of entrainment of elements of the same equivalent size is as follows: Polygnathus S. Ancyrodella Pa. Polygnathus Pa. Palmatolepis Pa. Polygnathus Pb. lcriodus Pa. Conodont elements grow by accretion of lamellae; to the first approximation. length is a satisfactory indication of size. Length can therefore be used to predict the settling velocities of elements, and which elements will sort together. Measurement of element lengths allows a rapid estimation of the degree of post-mortem sorting undergone by a sample and therefore its suitability for use in palaeobiological analysis. □ Conodont hydrodynamics, biostratinomy, drag coefficient, settling velocity. sorting. 相似文献
14.
The actual state of knowledge concerning the conodont animal is critically reviewed. All soft tissue documented by the specimens of the conodont animal were interpreted by the British collectors as Craniota (Vertebrata) features. Opinions on the precise affinities, however, remain controverse: The alleged chorda could have been a gut, bilateral symmetry, myomery, apatitic biomineralisation occur also in Invertebrata, caudal fins do in Chaetognatha. Even the lobes in the capital area interpreted as sensory organs could have served as aiding organs for food intake. Therefore, the originally sensational findings are reduced to the core issue that the conodont animal had an eel-like body and at the blunt end of it, behind peculiar lobes, the mineralized conodont elements were arranged. As a consequence, a relationship to the Protochordata cannot be excluded. A systematic position of the conodont animal as possible Vertebrata is likely only if organized below the Ostracodermata which is particularly so because conodonts occur so early in the Cambrian. In the second part of the article conodonts are discussed as guide fossils. The comprehensive, empirically grown taxonomy of the single elements is the prerequisite for recognizing outstanding, high resolution stratigraphy. In comparison, a multielement taxonomy remains as long problematical, as it is based on assumed, mostly statistically reconstructed rather than on natural multielement apparatuses. Taxonomical and nomenclatorial operations built on assumed apparatus affinity can bear heavily on nomenclature and stratigraphy of platform elements. It can be shown at the example of the Devonian that the platform elements have provided particularly in the pelagic facies a Standard Conodont Zonation that covers time almost without any gaps. The basis for this is that platform single element species and their phylogenetic development are extra-well known. In a special paragraph, history and applicability of the Standard Zonation is discussed in details. Different conodont biofacies are developed between the pelagic realm where the Standard Zonation originated, and the coastal areas so that conodonts can indicate temporal and bathymetric relationships of the mother rocks. In addition alternative conodont zonations were introduced mainly for the shallow water. Because of their conspicuous stratigraphic significance in the Devonian, conodonts were employed by International Committees to redefine Series and Stage Boundaries. For the boundary selection species were utilized from phylognetic lineages as only from tight evolution their point of origination could be well identified and recognized in worldwide correlation. The GSSPs (Global Stratotype Section and Point) within the Devonian are discussed in detail. In recent times, attempts are made at calibrating the duration of conodont zones on the basis of their well known rate of evolution and high temporal resolution. These analyses have to be continued in order to demonstrate the absolute time relationship of condont zones in more and continuous detail. Currently the phyletically controlled Standard Conodont Zonation is the authoritative stratigraphic method in the Devonian. It has provided together with the GSSPs precise and valuable fix points for a Global Time Scale (GTS). In combination with additional stratigraphie methods the Standard Conodont Zonation may provide further refinements in the future. 相似文献
15.
《Palaeoworld》2014,23(3-4):263-275
A fundamental aspect of taxonomy at the generic level, critical to understand Early Triassic conodont evolution, is the composition of the multielement apparatus. In this paper, we document a platform-bearing new conodont genus, Parafurnishius n. gen., as well as its multielement apparatus from the Griesbachian Feixianguan Formation (Lower Triassic) in Xuanhan County, northeastern Sichuan Province, southwest China. The new conodont genus is characterized by numerous robust and irregularly distributed conical denticles with variable platform morphology that has a possible affinity with the P1 elements of Furnishius. These genera have apparatuses similar to those of Ellisonia and are classified with the family Ellisoniidae. The strong intraspecific variation of P1 elements and the growth series within the entire sample population suggest that Parafurnishius may have evolved from the Griesbachian Isarcicella by developing random denticle positioning away from the platform centre, and then possibly evolved into younger Triassic Furnishius by developing a stable blade configuration. This preferred interpretation implies an ellisonid apparatus for Isarcicella. Alternatively, Parafurnishius may have evolved from Ellisonia and developed a homeomorphic P1 element with Isarcicella. This new taxon has strong intraspecific variation of denticle growth orientation during the Early Triassic. 相似文献
16.
GILBERT KLAPPER GRAEME M. PHILIP 《Lethaia: An International Journal of Palaeontology and Stratigraphy》1971,4(4):429-452
Recognition of four types of skeletal apparatuses of Devonian compound and platform conodonts, which conform in their basic plan to those already established in the Ordovician, Silurian, and Carboniferous, emphasizes the persistence of but a few structural types in the Paleozoic. The vicarious nature primarily of compound but also of platform elements in different multielement associations demonstrates mosaic evolution in Devonian apparatuses and has far-reaching taxonomic implications. Homologies of skeletal elements, for which a system of symbols is introduced, are evident in different apparatus types and show that the relationships of elements have been obscured by the older form taxonomy. Multielement analysis revises the taxonomic scope of the common Devonian genera, Icriodus, Polygnathus , and Ozarkodina. As a consequence of apparatus reconstruction, four new genera are proposed: Parapolygnathus, Cryptotaxis, Delotaxis , and Pedavis. 相似文献
17.
Victor H. Hitchings A.T.S. Ramsay 《Palaeogeography, Palaeoclimatology, Palaeoecology》1978,24(2):137-149
A functional model for the conodont apparatus is proposed based on Carboniferous bedding plane assemblages. It is proposed that the conodont assemblage functioned as a filter feeding and respiratory organ in organisms of unknown affinities, and that the organisation of elements in the assemblage genus Scottognathus can be used as a basic plan for interpreting the arrangement of conodont elements in other assemblages. In our model the Platform Blades opened and closed the anterior end of the system, the sieve consisted of Arched Blades, Pick-shaped Blades (assemblage genera Lewistownella and Lochriea) and the main cusps of the Elongate Blades; the denticulated bars of Elongate Blades and Pick-shaped Blades (form genera Scottognathus and Westphalicus) acted as a support for ciliated tissue. A radial and bilateral arrangement for the Elongate Blades is presented and discussed. Using this model as a guide we have reconstructed the assemblage genus Duboisella.The success of conodont organisms is attributed to the genetic plasticity of elements of the filter respiratory system, which enabled the system to adapt to evolutionary changes in the marine plankton. Ideas for further research are presented. In this account we have chosen to refer to the morphological form of conodont elements (Rhodes, 1954) rather than to the form generic and specific names assigned to them in the literature, e.g., we use the term Elongate Blades, instead of Hindeodella. 相似文献
18.
The application of high-resolution X-ray microtomography on conodont natural assemblages has provided new information on the structure of the elements and enabled the three-dimensional reconstruction of apparatuses. We herein report four conodont natural assemblages from uppermost Lower Qinglong Formation, Longtan, Nanjing, East China. Using X-ray microtomography, we reconstructed the apparatus of the end-Smithian (Olenekian, Early Trassic) Scythogondolella milleri. Our result confirms that Scythogondolella has an octomembrate apparatus composed of 15 elements (a single S0 element, two pairs of S1–4, M and P1–2 elements) like other gondolelloid apparatuses that have been tested by their corresponding natural assemblages, including Neogondolella, Novispathodus and Nicoraella. Element morphology of Scythogondolella closely resembles that of Neogondolella apparatus from the Illyrian (Anisian, Middle Triassic) of Monte San Giorgio: an alate (hibbardellan) S0 element with two long lateral processes that meet at a denticle anterior of the cusp, a bipennate (hindeodellan) S3 element with a bifurcated anterior process branching from the third denticle anterior of the cusp and an enantiognathiform S2 element with two dissimilar processes of nearly equal in length. It differs from the latter in the length of the inner-lateral process of M element and the posterior process of S0 and S3–4 elements without considering the obvious morphological differences in P elements between them. The element positional homologues of Scythogondolella conforms to those of the standard 15-element plan shared primitively among ozarkodinin, prioniodinin and prioniodontid conodonts, and again confirms that the breviform digyrate elements of cypridodellan and enantiognathiform morphotypes occupy the S1 and S2 positions, respectively, within the superfamily Gondolelloidea. 相似文献
19.
RICHARD J. ALDRIDGE DUNCAN J. E. MURDOCK SARAH E. GABBOTT JOHANNES N. THERON 《Palaeontology》2013,56(2):261-276
Abstract: Natural assemblages of a new conodont taxon, Notiodella keblon, from the Upper Ordovician Soom Shale Lagerstätte of South Africa contain 17 elements. This is the first time that a 17‐element apparatus plan has been unequivocally demonstrated in conodonts. The apparatus comprises paired P1, P2, P3, M, S1, S2, S3 and S4 elements and an unpaired, axial S0 element and provides a new template for use in the reconstruction of apparatuses from the collections of dispersed elements, particularly for those with icrion‐bearing P1 elements and perhaps for other balognathids. 相似文献
20.
Testing hypotheses of element loss and instability in the apparatus composition of complex conodonts: articulated skeletons of Hindeodus
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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. 相似文献