Attachment Scars Research Articles

Mongolitria: A new Early Cretaceous three-valved seed from Northeast Asia.

Fossil seeds recovered from the Early Cretaceous of Mongolia and Inner Mongolia, China, are described and assigned to Mongolitria gen. nov., a new genus of gymnosperm seed. Abundant lignitized seeds along with compression specimens isolated from the matrix were studied using a combination of scanning electron microscopy, anatomical sectioning, light microscopy, synchrotron radiation X-ray microtomography, and cuticle preparations. A single permineralized seed was examined by light microscopy of cellulose acetate peels and X-ray microtomography. Two species are recognized, Mongolitria friisae sp. nov. and Mongolitria exesum sp. nov. Both seeds are orthotropous with a short apical micropyle and a small, basal, circular attachment scar. The thick sclerenchymatous integument has a consistently three-parted organization and about 20 conspicuous longitudinal ribs on the surface. Mongolitria exesum differs from M. friisae primarily in its much larger size and thicker seed coat, which also preserves clear evidence of insect damage. Mongolitria is similar to other fossil seeds that have been assigned to Cycadales, but displays a unique combination of characters not found in any living or extinct cycadaceous plant, leaving its higher-level systematic affinities uncertain. Germination apparently involved splitting of the integument into three valves. Mongolitria was prominent among the plant parts accumulating in peat swamps in eastern Asia during the Early Cretaceous.

Kasimovian (late Pennsylvanian) cornute rugose corals from Egypt: taxonomy, facies and palaeogeography of a cool-water fauna from northern Gondwana

A strongly endemic Upper Pennsylvanian (Kasimovian) rugose coral association consisting of small, mostly non-dissepimented, simple structured and poorly diversified species is studied from the lower member of the Aheimer Formation (Western side of the Gulf of Suez, Egypt). The unit is composed of grey, silty mudstone intercalated with thin, ferruginous, silty dolostone–limestone and calcareous siltstone beds. Ten taxa from four families were identified. Four species of the Antiphyllinae are new; Actinophrentiscrassithecata n. sp., Lytvolasmaaheimerensis n. sp., L.paraaucta n. sp. and Monophyllumgalalaensis n. sp. Besides, Rotiphyllumexile de Groot, 1963 and Bothrophyllumokense Kossovaya, 2001 were identified; four taxa remain in open nomenclature (Lytvolasma cf. canadense, Zaphrentites cf. parallela, Zaphrentites sp. and Ufimia sp.). Rejuvenation, encrustation and bioerosion phenomena are rare. Attachment structures during mature stages are not evident; attachment scars in the apical parts are also rare. Growth patterns and embedding in the muddy deposits indicates that the corals lived as mudstickers in soft substrate. Recrystallization, dolomitization and ferrugination of open pore spaces inside the corals are the most common diagenetic features. The corals from the lower Aheimer Formation represent a typical cyathaxonid fauna that was adapted to high clastic input and turbid waters in a restricted, sheltered, episodically storm-swept inner ramp environment in an embayment of the southern shelf of the Palaeotethys. A time-averaged ramp model shows a regressive development from a mixed carbonate–siliciclastic open inner ramp setting during the Moscovian to the restricted inner ramp of the lower Aheimer Formation (Kasimovian) and following peritidal to fluvial environments of the Gzhelian. General and local palaeoclimatic considerations indicate cooling. Besides relations to northern Spain that root Egypt in the western Palaeotethys, connections existed via the Donets Basin (and the southern Urals) to the Cordilleran–Arctic–Uralian realm which is a cool water province during the Lower and Middle Permian. The Egyptian fauna appears to be a precursor of the anti-tropical cyathaxonid fauna of the latter time slice and also of the Lower Permian cool-water faunas of the east Cimmerian peri-Gondwana terranes.

Musculature of an Ordovician (Darriwilian) patelliform gastropod from Estonia

ABSTRACT A unique internal mould of the patelliform mollusc Eesticonus aariensis n. gen. n. sp. is described from the Middle Ordovician (Darriwilian Series, Kunda Stage) of northern Estonia. Well-preserved muscle attachment scars are compared to those of Floripatella from strata of Middle Ordovician (Dapingian Series) age in Utah, originally considered to be the oldest known patelloidean gastropod but possibly an untorted mollusc. Comparison with the muscle scar pattern in Archinacellina from the Ordovician of Bohemia suggests that Eesticonus is an archinacelloidean gastropod, but not a patellogastropod.

Taphonomic signatures on the pearl oyster Pinctada from Arabian Gulf, Saudi Arabia

A total of 886 valves of the pearl oyster Pinctada were collected from 12 sites in Al-Uqair beach along the Saudi Arabian Gulf coast in January 2021 in order to document their taphonomic signatures. Thirteen ichnospecies of 5 ichnogenera were identified and illustrated. These traces were produced by clionid sponges (Entobia cretacea, E. ovula, E. geometrica, E. laquea, E. cateniformis, Entobia isp.), durophagous drillers (Oichnus paraboloides, O. ovalis, O. simplex, and Oichnus isp.), traces of vermetid gastropods (Renichnus isp.) polychaete annelids (Caulostrepsis isp.) and barnacle attachment scars (Anellusichnus circularis). The Pinctada shells act as hard substrate for colonization by serpulid worm, Spirorbis sp., bryozoans, barnacles, and other bivalves. Ichnogenus Oichnus was the most abundant (53.73%), followed by Entobia (44.58%), Anellusichnus (0.51%), Caulostrepsis (0.34%), and Renichnus(0.84%). The thin-shelled and smooth skeletons of Pinctada were preferable for the abundant durophagous drillers (Oichnus traces) and clionid sponges (Entobia traces) during the lifetime of the pinctadas, in contrast to endolithic bivalves (Gastrochaenolites borings) which need thicker seashells for the settlement. Occurrence of different encrusters and bioeroders on the internal surfaces of many pinctadas confirmed the postmortem origin of the signatures. Disarticulation, fragmentation, and abrasion among the collected pinctadas might be attributed to their mode of life as epifaunal byssate, filter-feeder bivalves in the shallow littoral and sublittoral zones of the continental shelf under strong currents conditions.

Evidence of drilling predation in oysters from the Lower Cretaceous of the Neuquén Basin (Argentina) and its implications for Mesozoic predation trends

The study of trace fossils recorded on organic substrata is vital to the understanding of past biotic interactions. Here, oyster valves with circular holes are reported from the Lower Cretaceous (Berriasian to lower Valanginian) strata of the Neuquén Basin. From a total of 1318 oyster specimens, 17 valves presented 19 of these traces, which were studied to determine their origin, frequency and whether taxon, size and/or site selectivity existed. The studied traces, identified as Oichnus isp. (O. paraboloides in three cases), were recorded on four oyster species belonging to three genera: Aetostreon, Ceratostreon, and Nanogyra. Boring frequency was low (maximum = 0.103), and although traces were recorded exclusively on oysters, no taxon selectivity was found. No differences were found between the size of bored versus intact valves. The traces, although mostly recorded on left valves, showed a random distribution within valves, indicating no size or site selectivity. Hole morphology, absence of attachment scars and multiple holes point to a predatory origin. The lack of stereotypy indicates a generalist or facultative producer. Similar traces are usually ascribed to gastropod producers (i.e., naticids or muricids), but the gastropods co-occurring with the studied oysters lack any extant relative with a drilling apparatus. Hence, the producer remains unknown. This record contributes to the filling of the so-called early Mesozoic gap in drilling predation evolutionary history, during which two predation trends seem to have co-occurred: a background type of predation, carried out by generalists or facultative predators, and the rise of highly specialized predators, associated with the emergence of naticids and muricids.

Muscle attachment scars in helcionelloids from Denmark cast light on mollusc evolution in the Cambrian

Muscle attachment scars in helcionelloids from Denmark cast light on mollusc evolution in the Cambrian

Ghosts of the Holobiont: Borings on a Miocene Turtle Carapace from the Pisco Formation (Peru) as Witnesses of Ancient Symbiosis

In spite of the widespread occurrence of epibiotic turtle barnacles (Coronuloidea: Chelonibiidae and Platylepadidae) on extant marine turtles (Chelonioidea: Cheloniidae and Dermochelyidae), and although the association between these cirripedes and their chelonian hosts has existed for more than 30 million years, only a few studies have investigated the deep past of this iconic symbiotic relationship on palaeontological grounds. We describe probable platylepadid attachment scars in the form of hemispherical/hemiellipsoidal borings on an Upper Miocene (Tortonian) fragmentary turtle carapace, identified herein as belonging to Cheloniidae, from the Pisco Lagerstätte (East Pisco Basin, southern Peru). When coupled with the available molecular data, this and other similar ichnofossils allow for hypothesising that platylepadid symbionts were hosted by sea turtles as early as in early Oligocene times and became relatively widespread during the subsequent Miocene epoch. Chelonian fossils that preserve evidence of colonisation by platylepadid epibionts in the form of pits on the turtle shell should be regarded as fossil holobionts, i.e., palaeontological witnesses of discrete communal ecological units formed by a basibiont and the associated symbionts (including the epibiota). A greater attention to the bone modifications that may be detected on fossil turtle bones is expected to contribute significantly to the emerging field of palaeosymbiology.

BIOTIC INTERACTIONS BETWEEN CONULARIIDS AND EPIBIONTS FROM THE SILURIAN WAUKESHA BIOTA

ABSTRACTHere we describe an epibiont association between conulariids and holdfast producers, with attachment scars resembling those of the tubular epibiont, Sphenothallus, from the Silurian (late Telychian Series) Brandon Bridge Formation, Wisconsin. The conulariid population represents the most abundant sessile organisms in the Waukesha Biota and consists of two species, Conularia niagarensisHall, 1852 and Metaconularia cf. manni (Roy, 1935). Attachment scars present on the conulariid test offer a unique glimpse into the paleoecology of this Silurian benthic assemblage. However, body fossils of the attached epibiont are scarce and have not been observed attached or near conulariid specimens. This study evaluates the identity and paleoecological relationship between the conulariids and their enigmatic epibionts. Statistical analyses of attachment trace size, frequency, and distribution on the conulariid test gives insight to the nature of their symbiotic relationship. Our results did not find any significant support for a parasitic relationship. However, commensalism cannot be ruled out and serves as an alternative explanation for the relationship between these two organisms.

A Karethraichnus boring on a turtle shell bone from the Miocene of Italy is assessed as the attachment scar of a platylepadid symbiont

A Karethraichnus boring on a turtle shell bone from the Miocene of Italy is assessed as the attachment scar of a platylepadid symbiont

A new combination in Pseudolappula (Boraginaceae, Rochelieae) based on morphological, molecular and palynological evidence.

Lappulasinaica was recently transferred to the monotypic genus Pseudolappula based on phylogenetic studies, while the related species, L.occultata, has remained in the genus Lappula. In this study, morphological, molecular, and palynological evidence supports that L.occultata should be transferred to the genus Pseudolappula. Both L.occultata and P.sinaica share a combination of nutlets features that distinguish them from Lappula: a longer adaxial keel and a linear attachment scar. Phylogenetic analysis based on ITS and trnL-F strongly supports L.occultata as the sister taxon of P.sinaica. In addition, pollen grains of these two species are 3-syncolporate with 3 alternating pseudocolpi, which is significantly different from the grains of Lappula taxa. Based on the above evidence, the new combination Pseudolappulaoccultata is proposed.

Crinoids and blastoids, platyceratid gastropods and time: A taphonomic progression

Taphonomy aims to identify the history of preservation of a fossil, such as the order in which events occurred after death of the organism. For example, why are crinoid and blastoid thecae of Mississippian (Chadian) age never preserved in close association with parasitic/coprophagic platyceratid snails at Salthill Quarry, Clitheroe, Lancashire? They do occur in close juxtaposition at other localities globally where Upper Paleozoic strata crop out. We suggest that the intimate blastoid or crinoid/platyceratid association may occur at one of three identifiable levels. Level 1 includes those rare specimens of crinoids (not known in blastoids so far) that retain all arms and an attached platyceratid, a pattern of preservation indicating rapid burial causing death. Level 2 includes those thecae that have lost their brachioles (blastoids) or arms (crinoids), but still have an attached platyceratid. That is, the echinoderm has started to disarticulate following death, but the platyceratid continues to feed on the theca. In other words, and strangely, the snail is more intimately linked to the theca than certain of the echinoderm's appendages. Level 3 includes sites where crinoid/blastoid thecae and platyceratid conchs are preserved separately; determining if they were previously closely associated may be problematic unless attachment scars of snails are apparent on crinoid thecae. Suggestions that the pelmatozoan/platyceratid association involved aerosol filtration by the snail seem unlikely, because the intimate association is maintained after loss of the arms.

Rhizoid Structures of Axophyllum Cavum Trautschold, 1879 (Rugosa) in the Middle Carboniferous of the Moscow Basin: Morphology and Origin

Axophyllum cavum Trautschold, 1879 (Rugosa: Stauriida: Axophyllidae), a common solitary coral in the Moscovian stage of the Moscow Basin, is briefly redescribed. It is characterized by the small size of adult individuals (a few centimeters) and a high occurrence frequency of rootlet structures on the epitheca that supported the attachment of the coral on the substrate. The extensive collection of small-sized A. cavum (up to 2 cm) with various rhizoid structures and attachment scars from the Staryi Yam locality (Moscow area, Pakhra River, abandoned Yamskoi Quarry) was studied. The morphogenesis of rhizoids was is described in detail.

First authentic record of the freshwater turtle Mauremys from the Upper Pliocene of Italy, with a new occurrence of the rarely reported ichnotaxon Thatchtelithichnus holmani

Nowadays, the living species of the terrapin genus Mauremys (Testudinoidea: Geoemydidae) are mostly found in eastern Asia, but three of them inhabit the Western Palearctic ecozone. In Italy, occurrences of living individuals of Mauremys are interpreted as records of alien species; however, a growing fossil record demonstrates that this genus has inhabited Italy as recently as the Late Pleistocene. We report on a new fossil specimen of Mauremys from the Upper Pliocene (Piacenzian) marginal-marine deposits of Tuscany (central Italy). This find, consisting of a partial plastron and a loose neural, represents the second authentic report of Mauremys from the Italian Pliocene, as well as the first one from the Piacenzian of Italy. Therefore, it is a significant fossil that fills a gap in the chronostratigraphic distribution of Italian fossil Mauremys, helping – together with the Lower Pliocene holotype of Mauremys portisi – to bridge the rich Miocene and Pleistocene segments of this record. Moreover, two unusual scars observed on the external surface of the studied plastron are here referred to the ichnospecies Thatchtelithichnus holmani. These traces represent one of the few records worldwide of this rarely identified ichnospecies, as well as its geologically youngest published occurrence. Hypotheses regarding the origin of the Thatchtelithichnus traces are reevaluated, and an origin as attachment scars of aquatic ectoparasites (possibly ticks, leeches, or flukes) is reaffirmed as probable in cases of traces occurring on the exterior of the plastral bones of turtles.

New insight into the soft anatomy and shell microstructures of early Cambrian orthothecids (Hyolitha).

Hyoliths (hyolithids and orthothecids) were one of the most successful early biomineralizing lophotrochozoans and were a key component of the Cambrian evolutionary fauna. However, the morphology, skeletogenesis and anatomy of earliest members of this enigmatic clade, as well as its relationship with other lophotrochozoan phyla remain contentious. Here, we present a new orthothecid, Longxiantheca mira gen. et sp. nov. preserved as part of secondarily phosphatized small shelly fossil assemblage from the lower Cambrian Xinji Formation of North China. Longxiantheca mira retains some ancestral traits of the clade with an undifferentiated disc-shaped operculum, a simple conical conch with apical septa and a two-layered microstructure of aragonitic fibrous bundles. The operculum interior exhibits impressions of soft tissues, including muscle attachment scars, mantle epithelial cells and a central kidney-shaped platform interpreted as a support structure in association with its presumptive feeding apparatus. The muscular system in orthothecids appears to be similar to that in hyolithids, suggesting a consistent anatomical configuration among the total group of hyoliths. The new finding of shell secreting cells demonstrates a mantle regulating the mode of growth for the operculum. Investigations of shell microstructures support the placement of hyoliths as total group molluscs with an unsettled position within the phylum Mollusca.

Invertebrate epibionts on Ordovician conulariids from the Prague Basin (Czech Republic, Bohemia)

Approximately 4% of just over 5000 conulariids from ten Ordovician formations in the Prague Basin (Czech Republic) exhibit invertebrate epibionts and/or attachment scars. The commonest epibionts are craniid brachiopods followed by bryozoans and edrioasteroids, which are invariably articulated. Less abundant are monoplacophorans, Sphenothallus sp., ?Lichenocrinus sp., and an indeterminate invertebrate. Epibionts occur on Anaconularia anomala, Archaeoconularia, Conulariella sp., and Pseudoconularia grandissima, though predominantly on A. anomala and Archaeoconularia from open shelf deposits in the Upper Ordovician Letná and Zahořany formations, in which conulariids are substantially more abundant than in other formations. Epibionts on a particular conulariid belong to a single species or up to three species and major taxa. Except for monoplacophorans, epibionts occur on the external surface of the conulariids, in some cases with brachiopods, bryozoans, or edrioasteroids present on all four faces. Brachiopods and edrioasteroids present on all four faces show little variation between the faces in their size range. Also, brachiopods show apparent random trending of the antero-posterior axis, while edrioasteroids on some specimens of A. anomala and Archaeoconularia are preferentially centered on or near the facial midline. On schott-bearing specimens of A. anomala exhibiting brachiopods and/or edrioasteroids, these and other epibionts are absent on the schott. Bryozoans on some A. anomala and Archaeoconularia cover portions of all four faces and corners, and on two specimens of A. anomala the schott, too, is encrusted. A similar case involving edrioasteroids on Archaeoconularia sp. from the Upper Ordovician Upper Tiouririne Formation of Morocco is documented.These results highlight the importance of Ordovician conulariids as biological substrates, especially in Perunica and South Polar Gondwana, and indicate that encrustation occurred both on live individuals and on dead ones. The corners and midlines influenced the settlement and subsequent growth of brachiopods and edrioasteroids, and conulariids bearing these epibionts were buried catastrophically.

Quantitative Evaluation of Mantle Attachment Scars on the Shell of Margaritifera dahurica

The quantitative parameters of mantle attachment scars have been studied in freshwater mussel Margaritifera dahurica Middendorff, 1850 (Margaritiferidae, Bivalvia) for the populations of the Amur River (Zabaykalsky krai). It is shown that the density of mantle attachment scars is approximately the same for all shells studied, regardless of their age: an average of 0.72 attachment scars/cm2. According to a two-way analysis of variance, mantle attachment scars are distributed unevenly over the surface of the shell. Their density is the greatest at the caudal and anterial edges. The average diameter of mantle attachment scars for an individual depends on the length of the shell. This dependence can be described by the linear regression equation with a regression coefficient of 0.0012 ± 0.0001. Questions about the possibility of using the measured parameters to identify the species and/or genus of mollusks are discussed.

Experimental proof that multivariate patterns among muscle attachments (entheses) can reflect repetitive muscle use

Reconstructions of habitual activity in past populations and extinct human groups is a primary goal of paleoanthropological research. Muscle attachment scars (entheses) are widely considered as indicators of habitual activity and many attempts have been made to use them for this purpose. However, their interpretation remains equivocal due to methodological limitations and a paucity of empirical data supporting an interaction between systematic muscle forces and entheseal morphology. We have recently addressed the first issue with precise three-dimensional measuring protocols and rigorous multivariate analysis focusing on the patterns among different entheses rather than comparing each entheseal structure separately. In a previous study, the resulting entheseal correlations reflected synergistic muscle groups that separated individuals according to their lifelong occupational activities. Here we address the second issue by applying this methodology to existing micro-computed tomography data from rats that have undergone muscle stimulation under experimental conditions. In contrast to previous animal studies, we relied on blind analytical procedures across two research institutions and controlled for most factors of interindividual variability. Results demonstrated that the multivariate associations among different entheseal surfaces can directly reflect repetitive muscle recruitment and provide essential information on muscle use.

Deep-water cirripedes colonizing dead shells of the cephalopod Nautilus macromphalus from New Caledonian waters.

Fossil cephalopods are frequently encrusted by epibionts; however, determining whether encrustation occurred prior to or post‐mortem to the host, and whether the final environment of deposition corresponds to the habitat of encrustation is complex. The present paper describes cirripede epibionts, their calcareous bases and their attachment scars on 6 post‐mortem shells of Nautilus macromphalus, collected from deep water off New Caledonia. The cirripedes have left both cemented calcareous bases of Hexelasma and scars associated with bioerosion and discoloration produced by verrucomorph barnacles. Live cirripedes included a Metaverruca recta, with articulated opercular plates and organic tissue (on a shell that had been exposed on the sea floor for at least 150 years), and specimens of Hexelasma velutinum, one of which was partly attached to an internal surface of a shell. The disposition of verrucomorphs indicates that most Nautilus shells were colonized post‐mortem rather than during a floating stage. However, as cirripedes are known to have colonized living Nautilus, some Hexelasma, preserved only as calcareous eroded bases, may represent specimens that settled on a living Nautilus. The degree of bioerosion and discoloration induced by verrucomorph barnacles varies according to the surface preservation of Nautilus shells, with deeper and discolored traces preserved on old and degraded shells. Traces made by verrucomorphs described here are ellipsoidal and a new ichnotaxon, Anellusichnus ellipticus, is proposed to accommodate them. Importantly, verrucomorphs and other cirripede taxa with membranous bases that were attached to pristine shells may not leave any substantial scars, and, thus, will be difficult to detect in the fossil record.

Conch structures, soft-tissue imprints and taphonomy of the Middle Ordovician cephalopod Tragoceras falcatum from Estonia

Abstract Tragoceras falcatum (Schlotheim, 1820) is a common, loosely coiled estonioceratid (Tarphycerida, Cephalopoda) occurring in the Kunda Regional Stage (early Darriwilian, Middle Ordovician) of Estonia. Although the species is quite well-known, we document some features for the first time. For example, one specimen from the Harku quarry (Estonia) with a phosphatized replacement shell exhibits growth halts (megastriae) on the body chamber. As they are not preserved in smaller specimens, we suggest that these megastriae formed at the approach of maturity, possibly also reflecting sexual dimorphism and cycles of reproduction (iteroparity?). Additionally, the specimen shows minute soft-tissue imprints (drag bands and pseudosutures). These imprints are comparable to patterns in other cephalopods such as ammonoids, bactritids and other nautiloids, but have not yet been reported from Palaeozoic nautiloids. However, they might have been misinterpreted as oncomyarian muscle attachment scars previously. Lastly, we discuss the taphonomy of the specimen, which was encrusted by multiple bryozoan colonies post-mortem. Furthermore, it shows questionable traces of bioerosion.

Quantification of mantle attachment scars on the Margaritifera margaritifera (Margaritiferidae, Bivalvia) shell

A characteristic feature shared by all Margaritiferidae mussels consists in the presence of scars on the internal surface of their shells. These scars mark places of mantle attachment by specific epithelial cells. According to some authors, such parameters of mantle attachment scars as the density and degree of their manifestation can be used for the purposes of species identification. To this end, quality indicators (numerous or few, pronounced or poorly visible scars) are typically used; however, the use of quantitative criteria is preferable. This work was aimed at developing quantitative indicators of mantle attachment scars in the Margaritifera margaritifera freshwater pearl mussels for the populations of the Syuskyuyanyoki and Livoyoki rivers (Karelia). It is shown that the density and size of mantle attachment scars are approximately the same for all the investigated shell samples. These parameters display the absence of dependence on the age and size of molluscs. The regression coefficients for the linear dependence of the density or size of mantle attachment scars on the age or length of the shell show no significant difference from 0. For all the investigated molluscs, the density and size of mantle attachment scars are established to vary within the range of 0.37–1.16 scars/cm2 (0.71 ± 0.03 scars/cm2 on average) and 215–690 µm (417 ± 2 µm on average), respectively. According to a two-factor analysis of variance, the distribution of mantle attachment scars appears to be irregular across the shell surface. At the same time, a significant (p < 0.001) increase in their density is observed in the posterior and ventral directions, as well as diagonally in the posterior ventral direction. Issues associated with the application of the investigated parameters for the purposes of mollusc species identification are discussed.