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1.
Abstract: An unusual, bilaterally symmetrical black structure that embraces the protoconch and the phragmocone and is overlain by a rostrum has been studied in the Santonian–early Campanian (Late Cretaceous) belemnite genus Gonioteuthis from Braunschweig, north‐west Germany. The structure is here named the capsule. Energy dispersed spectrometry analyses of the capsule show a co‐occurrence of sulphur with zinc, barium, iron, lead and titanium, suggesting their chemical association. The capsule was originally made of organic material that was diagenetically transformed into sulphur‐containing matter. The material of the capsule differs from the chitin of the connecting rings in the same specimens. The capsule has a complex morphology: (1) ventral and dorsal wing‐like projections that are repeated in a breviconic shape of the alveolus, (2) an aperture with lateral lobes and ventral and dorsal sinuses copied by growth lines and (3) a ventral ridge that fits with the position of the fissure in the rostrum. The alveolus in the most anterior part of the rostrum is crater‐like. It is lined with thin, pyritized, laminated material, which appears to be the outermost portion of the capsule attached to the inner surface of the rostrum. A flare along the periphery of the alveolus marks a region where the rostrum was not yet formed, suggesting that the capsule extended beyond the rostrum. Modification of the skeleton in Gonioteuthis comprises a set of supposedly interrelated changes, such as innovation of the organic capsule, partial elimination of the calcareous rostrum and a diminishing of the pro‐ostracum, resulting in the appearance of a new type of pro‐ostracum that became narrower and shorter and lost the spatula‐like shape and gently curved growth lines of a median field that are typical for the majority of Jurassic and Cretaceous belemnites. The partial replacement of a calcareous rostrum with an organic capsule in belemnitellids may have been an adaptive reaction to an unfavourable environmental condition, perhaps related to difficulties in calcium carbonate secretion during the Late Cretaceous that forced animals to reduce carbonate production and to secret an organic capsule around the protoconch and the phragmocone.  相似文献   

2.
Early Jurassic belemnites are of particular interest to the study of the evolution of skeletal morphology in Lower Carboniferous to the uppermost Cretaceous belemnoids, because they signal the beginning of a global Jurassic–Cretaceous expansion and diversification of belemnitids. We investigated potentially relevant, to this evolutionary pattern, shell features of Sinemurian–Bajocian Nannobelus, Parapassaloteuthis, Holcobelus and Pachybelemnopsis from the Paris Basin. Our analysis of morphological, ultrastructural and chemical traits of the earliest ontogenetic stages of the shell suggests that modified embryonic shell structure of Early–Middle Jurassic belemnites was a factor in their expansion and colonization of the pelagic zone and resulted in remarkable diversification of belemnites. Innovative traits of the embryonic shell of Sinemurian–Bajocian belemnites include: (1) an inorganic–organic primordial rostrum encapsulating the protoconch and the phragmocone, its non‐biomineralized component, possibly chitin, is herein detected for the first time; (2) an organic rich closing membrane which was under formation. It was yet perforated and possessed a foramen; and (3) an organic rich pro‐ostracum earlier documented in an embryonic shell of Pliensbachian Passaloteuthis. The inorganic–organic primordial rostrum tightly coating the protoconch and phragmocone supposedly enhanced protection, without increase in shell weight, of the Early Jurassic belemnites against explosion in deep‐water environment. This may have increased the depth and temperature ranges of hatching eggs, accelerated the adaptation of hatchlings to a nektonic mode of life and promoted increasing diversity of belemnoids. This study supports the hypothesis that belemnite hatchlings were ‘a miniature of the adults’.  相似文献   

3.
Here we report the discovery of an Early Carboniferous (Late Visean) 3D cephalopod beak displaying significant similarity to the lower beak of Recent coleoids. It was uncovered in a fragmentarily preserved, longiconic shell from the Moorefield Formation in Arkansas, USA. This shell comprises a fractured 29‐mm‐long body chamber having a maximum diameter of ~14 mm and showing an indistinct pro‐ostracum‐like structure. The beak‐bearing shell could easily have been mistaken for a bactritid or orthocerid if it were not for a coleoid‐type, weakly mineralized, evidently organic‐rich shell wall which shows a lamello‐columnar ultrastructure of a bulk of shell wall thickness and plate ultrastructure of thin outer layer. The specimen is assigned to an as‐yet unnamed shelled coleoid of a so far unknown high‐level taxonomic group. A partially exposed, 4.0‐mm‐long portion of the beak is the lower beak in oblique view from its left side. It exhibits fractured anthracite‐like black, apparently originally chitin material, helmet‐like general shape, broad hood with narrow shallow median groove and small notch posteriorly, pronounced pointed, non‐biomineralized upside belt rostrum, high shoulder and about a 90–100 degrees jaw angle. A broad hood and massive rostrum emphasize its similarity to the lower mandible of Recent Vampyroteuthis and signify that its unique, among living coleoids, structure has been existed for at least since Late Visean time (~333 my).  相似文献   

4.
Data on the re‐examined‐type specimens of the Early Permian Glochinomorpha stifeli Gordon 1971 (Coleoidea, Cephalopoda) gives new insight into the evolutionary origination of gladius‐bearing coleoids in the Late Palaeozoic and suggests their parallel evolution with the belemnoids and phragmoteuthids. The iron‐oxidized arm hooks are found in front of a gladius on an un‐illustrated paratype (USNM 170614). They are dispersed in a maximum distance equal to 2.5 the gladius length from the incomplete anterior end of the rachis of the gladius. The hook height ranges from less than 1 mm to as much as 4 mm. They have a massive curved base, and a strongly curved shaft with a long thin distal part. The hooks confirm the cephalopod and the coleoid affiliation of G. stifeli that is widely rejected. The iron‐oxidized gladii (preserved length is less than 20 mm) show micro‐laminations and a fibrous ultrastructure; the fibre bundles are approximately 0.5 μm thick. Lack of calcium and the high content of nitrogen (up to 12% of total weight) confirm the originally non‐biomineralized (apparently chitin) composition of the gladii suggested by their fibrous ultrastructure. These data lead to the conclusion that in the evolutionary history of gladius‐bearing coleoids, the biomaterial (biochemical) development of the skeleton preceded its morphological transformation. This phenomenon resulted in a recombination of an advanced composition (being non‐biomineralized) with archaic features (sensu morphological structure of the posterior part) in the gladius of G. stifeli. The data cast doubt on the hypothesized origination of a gladius from a phragmoteuthid pro‐ostracum as well as the evolutionary origination of the gladius‐bearing coleoids from pro‐ostracum‐bearing phragmoteuthids or belemnitids.  相似文献   

5.
A morphological comparison of shell‐muscle contacts in coleoid cephalopods mainly from the Early Jurassic (Toarcian) Posidonia Shales of Holzmaden (Germany), the Middle Jurassic (Callovian) Oxford Clay of Christian Malford (UK), Late Jurassic (Kimmeridgian‐Tithonian) plattenkalks of Solnhofen (Germany), and the Late Cretaceous (Cenomanian) of Hâdjoula and Hâkel (Lebanon) provides new and meaningful insights into their locomotion systems. The study shows that both pro‐ostracum‐ and gladius‐bearing coleoids are typified by a marginal mantle attachment and by distinctly separated fins, which usually insert (indirectly via the shell sac and basal fin cartilages) to posterior shell parts. While absent in gladius‐bearing forms, mantle‐locking cartilages might have existed already in pro‐ostracum‐bearing belemnoids. Similar to ectocochleate ancestors, funnel‐ and cephalic retractors are generally attached to the internal (ventral) shell surface. A comparison of Mesozoic and Recent gladius‐bearing coleoids shows that the locomotion system (most significantly the dorsal mantle configuration, and the presence of nuchal‐ and funnel‐locking cartilages) is fundamentally different. This does not support the concept of ‘fossil teuthids’, but suggests, owing to similarities with Recent Vampyroteuthis, placement of Mesozoic gladius‐bearing coleoids within the Octobrachia (Octopoda + Vampyromorpha). Classification of Mesozoic gladius‐bearing coleoids as octobrachians implies that: (1) unambiguous teuthids are still unknown in the fossil record and (2) the similarity between Recent and some fossil gladiuses represents a matter of homoplasy.  相似文献   

6.
Paysandisia archon (Burmeister, 1880) is an attractive neotropical castniid moth whose presence in Europe was recently reported. Its larvae are endophagous, feeding inside the trunks and branches of several species of palm trees (Arecaceae). The present paper deals with the morphology and biometry of the egg of this moth, comparing them with those of other castniid species.

The egg is a typical castniid egg, fusiform, upright sensu Döring, light cream or creamy pink when freshly laid, 4.69 ± 0.37 mm long and 1.56 ± 0.11 mm wide. Larvae emerge by gently splitting the chorion along one of the longitudinal ridges, on the half closer to the micropyle. SEM, TEM and LSCM photographs showing ultrastructural details of the egg are shown for the first time. The micropylar rosette (c. 54 μm in diameter) has generally 14–17 cells; in its centre lies the micropylar pit (c. 6 μm in diameter) which bears 12–16 micropylar canal openings (= micropyles) around its periphery. The pathways followed by those canals through the chorion have been figured. Eggs sampled in the wild (so laid by several females) were found to have a slightly variable number of ridges: most bore seven ridges (68.87%), although a significant portion (30.46%) bore eight and 1 egg (0.67%) bore only six; this against the currently accepted rule of five‐ridged eggs for Castniini (i.e. Neotropical castniids) to which Paysandisia archon belongs. It has also been found that the same female specimen has the capability of producing six‐, seven‐ or eight‐ridged eggs. Five types of egg irregularities affecting the longitudinal ridges are also figured and described. Transverse striae on the egg of P. archon are about 122. Aeropyles (c. 4 μm in diameter) occur on the ridges, at the intersections between the latter and two contiguous (left and right of the ridge) transverse striae, amounting to c. 854 on a seven‐ridged egg and to c. 976 on an eight‐ridged egg. Occasionally minute aeropyles ('microaeropyles') (c. 1.96–3.13 μm in diameter) also occur on transverse striae located close to both egg poles.

The chorion of P. archon shows the typical ditrysian fine structure with very thin basal layer (C‐1), 0.3–0.2 μm thick, gas‐filled trabecular layer (C‐2), c. 0.9 μm thick, and lamellar layer (C‐3), its thickness varying between 18.5 and 13 μm due to the bumpy external surface of the chorion. Aeropylar canals, that penetrate layer C‐3, connect the air‐containing inner chorionic meshwork (the trabecular layer C‐2) with the surrounding air; their outer part forms a big bulbous cavity (which opens to the outside through the small opening seen in external SEM images) and, underneath, a narrow canal follows, leading into the trabecular layer (C‐2).  相似文献   

7.
Abstract: Groenlandibelus rosenkrantzi from the Maastrichtian of Greenland has long been thought to constitute an early representative of spirulid coleoids. This study shows that this view must be reassessed, at least in part. A re‐investigation of the types and of material recorded subsequently has revealed that none of these specimens is conspecific with the holotype of G. rosenkrantzi. Cyrtobelus birkelundae gen. nov, sp. nov. differs from the type of G. rosenkrantzi in having lower chambers and in lacking an apically elongated sheath. The longiconic phragmocone of G. rosenkrantzi has more features in common with the presumed spirulid genus Naefia. A specimen described in detail by J. A. Jeletzky in the mid 1960s as ‘G. rosenkrantzi’ is designated holotype of C. birkelundae sp. nov., which means that internal phragmocone features are still unknown in G. rosenkrantzi. Cyrtobelus hornbyense gen. nov, sp. nov. from the Campanian of western Canada constitutes the first record of early spirulids from the northeast Pacific, being based on seventeen extraordinarily well‐preserved phragmocones. This species differs from C. birkelundae sp. nov. only in the width of the siphuncular tube. The presence of a caecum, a nacre‐less conotheca that represents the continuation of the protoconch conotheca, conothecal flaps that anchor the mural parts of the septa, and a thin investment‐like sheath are characters shared only with Recent Spirula. In particular, the unusual protoconch architecture of Cyrtobelus gen. nov. challenges a phylogenetic origin within bactritoid‐like coleoids.  相似文献   

8.
HENNING BLOM 《Palaeontology》2012,55(3):641-652
Abstract: A new possible stem gnathostome, Kerreralepis carinata gen. et sp. nov., is described on the basis of a single specimen from the Lower Devonian of the island of Kerrera in the Inner Hebrides, Scotland. It is recognized as an anaspid by the chevron‐like arranged rod‐shaped scales on the trunk, gill openings extending behind the orbits in a slanting row and a series of median dorsal ridge scales. This specimen also has a series of median ventral plates, indicating the presence of a preanal fin‐fold, which in turn has consequences for interpretations of other problematic stem gnathostomes and their phylogenetic context. A cladistic analysis supports a monophyletic Anaspida including the scale‐covered birkeniids but excluding Lasanius as well as anaspid‐like forms such as Euphanerops and Jamoytius. The establishment of a new genus and species increases the diversity of anaspids and allows for a more detailed study of anaspid interrelationships. An ingroup analysis using Lasanius as an outgroup resolves Birkenia as a rather basal anaspid, sister to all other anaspids, alternatively sister to a clade represented by the taxa from Ringerike, Norway, and the closely associated taxon from Saaremaa Island, Estonia. These topologies agree rather well with the present fossil record of anaspids.  相似文献   

9.
A new vampyropod coleoid from the Cenomanian limestones of Coahuila (Mexico) is described. Glyphiteuthis rhinophora n. sp. is classified as a member of the Trachyteuthididae because of its general gladius morphology. Within the genus Glyphiteuthis, Gl. rhinophora n. sp. is unique by its nose-shaped extension of the anterior median field extremity. The ventral gladius surface reflects the dorsal surface and lacks evidence of a phragmocone, so affiliations with sepiids are unlikely. Gl. rhinophora n. sp. represents the first Cenomanian record of a vampyropod coleoid in the New World and the first evidence of the genus outside the Tethyan and Boreal realm. The paleoenvironment indicates a nektonic lifestyle for Gl. rhinophora n. sp.  相似文献   

10.
An electromagnetic radiation field within a biological organism is characterized by non-local interference. The interfering beams form a unitary tridimensional network with beams of varying intensity, also called striae, which are distributed on the organism surface. These striae are equivalent to semi-reflectors. The striae carry bio-information of corresponding organs and, thus, integrate all tissues, and organs of the organism. The longitudinal striae are classified as channels, while the transverse striae are collaterals. The acupoints are seen as the points where electromagnetic interfering striae intersect or converge. This hypothesis builds a foundation to understand the traditional Chinese medicine, including acupuncture, from the perspective of scientific knowledge.  相似文献   

11.
Abstract To clarify the dynamic construction of Allomyrina dichotoma (Linné) elytra, the distribution of trabeculae and surface structures has been investigated using scanning electron microscopy and transmitted light. There are solid trabeculae in the elytron and under penetrating light these can be seen as black dots. It is clear that trabeculae arrangement is almost entirely irregular throughout the elytron, except for some approximately straight alignment near some trachea. This irregular arrangement is different from the longitudinal rows of striations that are well known in other species, and there are no hollowed striae (punctures) on the elytral surface of A. dichotoma . Throughout the internal architecture of the elytron, there are mesh-like (honeycomb) structures. Each honeycomb usually has 1–2 trabeculae mainly distributed at the corners of the honeycomb. The number of trabeculae present on each honeycomb is dependent on the size of the honeycomb.  相似文献   

12.
13.
Two new species of Martensia (Delesseriaceae, Rhodophyta) are described from Jeju Island, Korea. Martensia jejuensis is characterized by the thallus of long linear axes and a proximal membranous part (initial blade), the linear axes that are derived from the longitudinal lamellae of the latticework, the flabellate bladelets arising from the linear axes terminally and laterally, the leading margins of the latticework giving rise to spine‐like or spatulate projections at intervals, and tetrasporangia borne on the whole thallus except for the spatulate projections. Martensia bibarii is characterized by the fimbriate aspect, the ribbon‐like blade with lobes, the flabellate bladelets derived from the lobes of the blade, the bladelets bearing the fringe or the latticework distally, the fringe consisting of many fine and strap‐shaped lamellae, and tetrasporangia borne only on the blade.  相似文献   

14.
The pretarsus of the female miteVarroa jacobsoni Oudemans (1904) consists of two main parts, a cuticular basal stalk and an extrudable, membranous ambulacral pad, the caruncle. The caruncle, when fully extruded and expanded, becomes a bilobed sucker, and when deflated, the entire caruncle is retracted into the basal stalk. The basal stalk of the pretarsus with the sucker fully retracted into it resembles an inverted cone with its narrow portion attached to the apex of the tarsus. The basal stalk consists of three large plates; two lateral and one median. The proximal end of each lateral plate bears a sclerotized claw-like structure which functions to support the expanded caruncle. The median plate possesses a long, narrow ridge process connecting the basal stalk with the caruncle, and functions to control retraction and protraction of the caruncle. The morphology and function of the basal stalk suggest that the claw-like structure are the ungues; the median plate is the unguifer, and the median ridge is the tendon of the retractor/depressor muscles of the pretarsus. The significance of the pretarsal suckers to the control of the mite is also discussed.  相似文献   

15.
Dictyoconites from the middle Triassic Cassian Formation is a characteristic representative of the Aulacocerida. Embryonic development and construction of the phragmocone is like that of Jurassic belemnites. The siphuncular tube is double-walled with a long retrochoanitic mineralized septal neck continuing into an organic tube. The extended decoupling zone resembles that ofSpirula. Characteristic ofDictyoconites are the tubular »living chamber« and two layered deposits of the muscular mantle on the phragmocone. The Triassic coleoid was a slender squid with visceral mass and mantle cavity encapsuled in shell and the whole conch covered by muscular mantle extending in two lateral apical fins attached to the aragonitic rostrum.  相似文献   

16.
Subfossil remains of an unknown chydorid taxon were found in sediments of three lake basins in Finland. Two of the sites lie in southern Finland and one in NW Finnish Lapland. Similar remains are also known from four lakes in eastern Finland. The headshields are small, with a broadly rounded posterior margin and an attenuated rostrum. The headshields resemble those of Rhynchotalona falcataSars, but have a unique pore arrangement. There is one oval median pore near the posterior margin and two lateral pores which are displaced quite far in position. The shell is very small and has faint, longitudinal striae. Also, unknown postabdomens were found. These resemble postabdomen of R. falcatain shape but had 5–6 pairs of teeth instead of the 2 seen in R. falcata. The age of the remains varies between ca. 8500 14C yr BP and recent decades. The species appears to have been present in the entire country during most of the Holocene. On the basis of the pore arrangement, the new species cannot be put into any previously known genus. A tentative name Unapertura latensn. sp. is suggested until intact specimens are found and described.  相似文献   

17.
A new species of Cryphodera Colbran, 1966, parasitic on wild rose (Rosa sp. L.), is described from Utah, USA. Cryphodera utahensis n. sp. most closely resembles C. podocarpi (Wouts, 1973) Luc et al., 1978, but is distinct with respect to a number of characters including juveniles with a longer esophagus (206 versus 142 μm), shorter tail (47 versus 69 μn), and four rather than three incisures in the lateral field. Females of C. utahensis have a terminal protuberance which is more pronounced than in other species. Scanning electron microscope observations of the lip region of males indicate a labial disc surrounded by six lip sectors. However, the remainder of the lip region is comprised of irregularly-shaped plates; similar patterns with longitudinal striae apparently characterize males throughout the genus. The lip pattern of juveniles of C. utahensis n. sp. includes an oval labial disc surrounded by six lip sectors; transverse striae extend the height of the lip region without longitudinal striae. The type locality of C. utahensis confirms a broader distribution of the genus than was indicated for other species, which are limited to Australia (Queensland) and New Zealand.  相似文献   

18.
Tsujino, Y & Shigeta, Y. 2012: Biological response to experimental damage of the phragmocone and siphuncle in Nautilus pompilius Linnaeus. Lethaia, Vol. 45, pp. 443–449. Three adult specimens of Nautilus pomplilius Linnaeus from the Philippines were experimented on to estimate the biological response to damage of the phragmocone and siphuncle in this cephalopod mollusc. In addition, the data obtained from the experiments were used for discussion of shell damage in ammonoids and in other extinct cephalopods. Specimen’s phragmocone and siphuncle were perforated and severed artificially, followed by observations in the laboratory tank during periods of 75 and 132 days. For at least 2 or 3 months, all individuals survived after damage to the phragmocone and siphuncle despite loss of neutral buoyancy. Based on our observations after completion of the experiments, the severed adoral remaining part of siphuncle healed by the siphunclar epithelium. In addition, perforation of the phragmocone was partly repaired by shell secretion from the dorsally extending mantle due to subsequent volution of shell growth. Our experiments revealed that damage to the phragmocone and siphuncle in Nautilus was not necessarily a lethal injury. It may be possible that such biological response also applies to extinct ammonoids and nautiloids. In a similar case of extinct ammonoids and nautiloids, damage to their phragmocone and siphuncle may also not have been a lethal injury as with Nautilus. However, some factors leading to death are likely to be dependent on the degree of damage to the phragmocone and siphuncle and influence of hydraulic pressure. □Ammonoids, injury, nautiloids, Nautilus, phragmocone, repair, siphuncle.  相似文献   

19.
Abstract: The complete neurocranium plus palatoquadrate of the plagiosaurid temnospondyl Gerrothorax pulcherrimus from the Middle Triassic of Germany is described for the first time, based on outer morphological observations and micro‐CT scanning. The exoccipitals are strong elements with paroccipital processes and well‐separated occipital condyles. Anterolaterally, the exoccipitals contact the otics, which are mediolaterally elongated and have massive lateral walls. The otics contact the basisphenoid, which shows well‐developed sellar processes. Anteriorly, the basisphenoid is continuous with the sphenethmoid region. In its posterior portion, the sphenethmoid gives rise to robust, laterally directed laterosphenoid walls, a unique morphology among basal tetrapods. The palatoquadrate is extensively ossified. The quadrate portion overlaps the descending lamina of squamosal and ascending lamina of pterygoid anteriorly, almost contacting the epipterygoid laterally. The epipterygoid is a complex element and may be co‐ossified with otics and laterosphenoid walls. It has a broad, sheet‐like footplate and a horizontally aligned ascending process that contacts the laterosphenoid walls. The degree of ossification of the epipterygoid, however, is subject to individual variation obviously independent from ontogenetic changes. The stapes of Gerrothorax is a large, blade‐like element that differs conspicuously from the plesiomorphic temnospondyl condition. It has a prominent anterolateral projection which has not been observed in other basal tetrapods. Morphology of neurocranium and palatoquadratum of Gerrothorax most closely resembles that of the Russian plagiosaurid Plagiosternum danilovi, although the elements are less ossified in the latter. The extensive endocranial ossification of Gerrothorax is consistent with the general high degree of ossification in the exo‐ and endoskeleton of this temnospondyl and supports the view that a strong endocranial ossification cannot be evaluated as a plesiomorphic character in basal tetrapods.  相似文献   

20.
Klug, C., Schweigert, G., Fuchs, D. & Dietl, G. 2009: First record of a belemnite preserved with beaks, arms and ink sac from the Nusplingen Lithographic Limestone (Kimmeridgian, SW Germany). Lethaia, 10.1111/j.1502‐3931.2009.00203.x A recent discovery of an unusually preserved belemnite from Nusplingen comprises the extraordinarily rare remains of beaks and nearly in situ arm hooks, as well as the ink sac and an incomplete phragmocone. So far, Hibolithes semisulcatus ( Münster, 1830 ) is the only belemnite known from the Nusplingen Lithographic Limestone (Upper Jurassic, Late Kimmeridgian, Beckeri Zone, Ulmense Subzone; SW Germany) that has the same phragmocone shape and size, and thus we assign the new specimen to this taxon. The rostrum was probably lost due to a lethal predation attempt in which the prey was killed but not entirely eaten. For the first time a specimen reveals details of the belemnite beak morphology, which we compare with the beaks of other Jurassic coleoids. This specimen presently represents the only known rostrum‐bearing belemnite of post‐Toarcian age with preserved non‐mineralized body parts. With the new discovery, Nusplingen now represents the only locality which has yielded complete beak apparatuses from all major Jurassic cephalopod groups. □Beaks, Belemnitida, Coleoidea, Germany, Late Jurassic, morphology, taphonomy.  相似文献   

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