The M & oacute;jcza Limestone Formation exposed in the Holy Cross Mountains in southern Poland, being a part of the Ma & lstrok;opolska microcontinent in the Ordovician, abounds in phosphate-coated originally calcareous fossils of microscopic size. Their geological age covers most of the Mid and Late Ordovician. The late Katian topmost bed of the Formation is especially rich in phosphatized larval and early postlarval gastropod conchs and yielded 8703 specimens taxonomically determinable at least at the genus rank. High-spired trochonematid conchs ornamented with delicate spiral striation between low ribs dominate the assemblage. Unlike other gastropod communities of similar age, this one was poor in bellerophontids and openly coiled platyceratids and despite the geographic proximity, the typically Baltic planispiral leseurillids are extremely rare. Comparable gastropod assemblages are unknown from the Perunica and Avalonia microcontinents or the continental Gondwana. Instead, specimens representing a few species of probable holopeids with smooth shell surface are abundant. Their conch geometry ranges from that already known among holopeids to the virtually planispiral, superficially resembling both, the coeval Baltic leseurillids and geologically younger euomphalids. Presumably, this taxonomic composition of the M & oacute;jcza gastropod community was a result of local speciation with a significant contribution from homoplasy to its taxonomic diversity. center dot Key words: palaeobiogeography, Palaeozoic, phosphatization, molluscs, Bellerophontida, Jinonicella.

Hyoliths were extinct invertebrates with embryonic and larval conchs closely similar to those of the conchiferan molluscs. Yet, they lacked radula and were equipped with a tentacular oral apparatus. To resolve their phylogenetic affinities, it is necessary to determine taxonomic strength of particular aspects of their anatomy. Along with the early Palaeozoic 'taphonomic windows', offering data on the hyolith soft anatomy, the phosphatized 'small shelly fossils' assemblages with a high contribution from hyoliths are the main source of evidence on the ontogeny of their skeletal aspects. In this study, one of the latest comes from the Late Ordovician M & oacute;jcza Limestone, Poland, and one of the earliest from the Early Cambrian Sellick Hill Formation at Mayponga Beach, South Australia. It appears that irrespective of the adult anatomy, the ontogeny of various hyoliths was closely similar to that of the early Palaeozoic gastropods and orthoceratid nautiloids. Their embryonic trochophore stage conchs were bulbous, with apical mucro. After hatching, the larva secreted a cylindrical conch. The mode of larval development seems to be independent of whether the post-larval tentacular apparatus and simple U-shaped intestine was used to filtration of organic matter (hyolithids), or rather the mud was collected and digested in the complexly folded intestine (orthothecids). A smooth cup-like operculum developed already at the trochophore stage. The post-larval hyolith conch shapes, ranging from strongly convex to concave venter, apparently represented various adaptations to passive lying on the sea bottom. Instead, the laterally compressed Turcutheca-like conchs suggest an erect pose and free life, offering a link to the more-or-less conical conchs of the helcionellid molluscs. The change from such epibenthic vagile mode of life to a passive filtration, which is not necessarily inconsistent with the molluscan affinity of hyoliths, may explain the loss of radula by analogy with bivalves. square Phosphatization, Cambrian, Ordovician, Australia, Poland, Hyolitha, filtrators, ontogeny

A sample of phosphatized, originally calcareous, mollusk shells from the Katian age uppermost M & oacute;jcza Limestone at its type locality yielded a few hundred polyplacophoran plates. The chelodids are very rare among them. Three septemchitonid species dominate. They represent a gradation from underived steep roof-like plates to almost cylindrical ones, leaving only a narrow ventral slit for the foot. Apparently, this represents the first step toward the extremely derived 'segmented clam' Bauplan of the Silurian Carnicoleus, with plates completely closed at the venter except for the mouth and anal openings. To enable growth, the plates became thinner and more flexible (or perhaps resorbed) along the dorsum. The tendency toward reduction of the ventral gap of the plates in the early Paleozoic septemchitonid polyplacophorans implies their lack of ability to cling to the substrate with a muscular foot. In compensation, their plates changed toward a more efficient protective function, covering the animal body sides more and more completely. This may explain the origin of the ventral furrow of extant solenogasters hiding the rudimentary foot. An opposite route was chosen by the coeval Acaenoplax lineage, in which the plates did not contact each other, exposing much of the soft body on the dorsum. In both cases the animals appeared to be worm-like, perhaps representing different ways of evolution from the Paleozoic chitons to the extant aplacophorans. A septemchitonid polyplacophoran from the M & oacute;jcza Limestone (central Poland) represents the first step toward the "segmented clam" Bauplan of the Silurian Carnicoleus, with plates completely closed at the venter except for the mouth and anal openings. To enable growth, the plates became thinner and more flexible (or perhaps resorbed) along the dorsum. This may explain the origin of the ventral furrow of extant solenogasters hiding the rudimentary foot. image

Continental drift of Baltica from the Tremadocian subpolar latitudes to subtropical latitudes in the Katian was the main factor controlling the succession of the Ordovician Baltic conodont communities. These faunas were gradually enriched during the Floian as a result of immigrations from the regions experiencing warmer climate. Reinterpretation of quantitative data in terms of population approach to fossil assemblages shows how some of these immigrants evolved anagenetically in place, changing their contribution to the secondary productivity of the ecosystem. The composition of the fauna became surprisingly uniform, at least since the numerical domination by the presumably indigenous Baltoniodus lineage was established during the Dapingian. Baltoniodus was supplemented by another indigenous lineage of Trapezognathus-Lenodus-Eoplacognathus, which continued its subordinate occurrence during the Darriwilian. The early Sandbian transgression resulted in immigration of the Amorphognathus lineage that emerged allopatrically in an unknown region but then began evolving anagenetically until the end of the Ordovician. Conodonts with coniform apparatus elements added complexity to the general picture of immigrations and disappearances, but only the lineage of Protopanderodus rectus seems to have differentiated geographically its contribution to the biological productivity. Several brief cooling and warming episodes did not result in any long-term transformations of the conodont communities. Most intriguing was the immigration of the Yaoxianognathus lineage that probably gave rise to all of the post-Ordovician ozarkodinids. By that time, Yaoxianognathus had its close relative in the tropical North American Midcontinent, but the source area was probably in the Darriwilian of the Argentinian part of Gondwana. Forms with thin P-1 elements of basal cone walls, like Scabbardella or Hamarodus, are indicators of glacial Gondwanan influences. The lineage of Sagittodontina, associated with these in the Ma & lstrok;opolska microcontinent (with Gondwanan affinities), was subordinate in Baltica until it had been influenced by the Hirnantian glaciation that ended the Baltic conodont fauna.

The dasycladacean nature of the receptaculitids, originally a result of misunderstanding of the fossil evidence, is widely accepted and entered textbooks but their alternative interpretation as sponges remains a possibility. Phosphatized, originally aragonitic, late Ordovician receptaculitid meroms, more complete than those previously known, may help in determining more precisely their taxonomic identity. Some of them may lack column or cap, but acutely-pointed arms parallel to the body surface are invariably present, which supports the poriferan ties. The spinose character of meroms and the presence of growth increments on meroms' caps and feet in advanced receptaculitids preclude their algal affinity. The walls of underived receptaculitids with conical body cemented to the substrate were perforated with pores that may be interpreted as inhalant canals in terms of the sponge model. Possibly, the receptaculitid lineage emerged more or less synchroneously with those of sponges having siliceous, aragonitic or calcitic skeletons in result of selective pressure from newly evolved macroscopic predators. The meroms of advanced globular receptaculitids were fused in the basal portion of the body and remain loose in the upper part, where their caps remain tightly arranged. In both body regions no space was left for any porosity. This suggest that the meroms were free to move in a certain extend allowing water to penetrate the body. Such ability would not be consistent with their algal nature but is within potential of the physiology of sponges owing to contractile action of the pinacoderm. Presumably, in the post-Cambrian evolution of the receptaculitid lineage the ability of aneural signal transduction by pinacocytes was mastered. square dasyclads, Ordovician, phosphatization, Poland.

The Devonian-Carboniferous boundary is allegedly marked by one of the most catastrophic global extinctions associated with sedimentation of the Hangenberg black shale. A dense sampling of the Kowala section in the Holy Cross Mountains, Poland, challenges this view, showing that the faunal dynamics across the Hangenberg black shalewas not more dramatic than that across the preceding Kowala black shale. Quantitative analysis and biologically meaningful conodont apparatus study of the Kowala material offer probably the most complete record of faunal change in the latest Famennian and earliest Tournaisian among those sampled bed-by-bed for ammonoids and conodonts. It appears that the faunal dynamics of both cephalopods and conodonts was controlled by environmental changes that resulted in numerous immigrations and disappearances of particular lineages. Only a small fraction of lineages persisted long enough at the place, and transformed their morphology fast enough, to leave a record of their evolution. Most of the evolution apparently took place elsewhere. Locations of remote refugia where these lineages evolved in the time span bracketed by the Kowala and Hangenberg black shale events remain to be identified. Conodont apparatus study on geographically distant Vietnamese locality Cat Ba provides evidence that at least in the latest Famennian some conodont species unknown from Poland were present in Vietnam. Moreover, the contribution of species known from both localities to Polish and Vietnamese fossil assemblages was dramatically different.

Until recently virtually nothing was known about the morphology of conodont animals, and zool­ ogic affinities of the group are still regarded as ob­ scure. The present contribution evaluates the hy­ pothesis that agnathan vertebrates are the closest relatives of conodonts. The microstructure of ele­ ment of conodont apparatuses, their organization into skeletal structures, and the inferred morphol­ ogy of the soft body parts are compared to the anatomy of early vertebrates. Other problematic phosphatic dermal sclerites are also reviewed. A complete phosphatic element of the cono­ dont apparatus consists of two distinct parts. The oral part (crown of Nicoll 1977) is developed by centrifugal external accretion. It is rather compact in structure, and its surface is smooth or regularly ornamented. The basal part (basal filling), which is developed by inner accretion, varies greatly in microstructure and morphology. The mode of se­ cretion of the crown tissue is here considered di­ agnostic for the group; fossil sclerites secreted dif­ ferently are not considered to be conodont elements (see Bengtson 1976, 1983a, for opposing view).

An instructive introduction to the theory of evolution and its applications in biology, physics, chemistry, geology and humanities. The author shows that evolution is a physical process, occurring in geological time dimension, describes how the Darwin’s theory of natural selection works in immunology, neurobiology, sociology as well as in certain aspects of culture and political institutions. He also shows the effects achieved through the action of selection in different areas of biological and social life. He discusses such problems as: the ambiguity of the term “theory of evolution”, the falsifiability of evolutionary hypotheses, connection between evolution and thermodynamics, the concept of reductionism, methodological background of phylogenetics, cladistics, evolutionary developmental biology and homeotic genes, as well as the cumulative nature of social and cultural evolution.

A fossil larva lacking segmentation of the calcified carapace, closely resembling the trilobite protaspis, has been found associated with other skeletal elements of an angarocaridid Girardevia species in the mid Darriwilian of central Siberia. The presence of protaspis larvae in the angarocaridids, generally believed to represent a branch of the Aglaspidida, supports their proximity to trilobites and proves a low position on the arthropod phylogenetic tree but does not necessarily contradict the chelicerate affinity. The cephalic appendages of angarocaridids bore massive gnathobases with detachable spines, closely similar to those known in extant xiphosurans and in their probable Cambrian relatives. The stratigraphic succession of the angarocaridids, their phosphatized cuticle pieces being abundant in the Ordovician strata of Siberia, shows a gradual improvement of mechanical resistance of their carapaces, eventually resulting in a honeycomb structure. The associated benthic mollusc assemblage is dominated with the bellerophontids showing high mortality at metamorphosis and only the limpet-like Pterotheca, infaunal bivalves, and scaphopods being able to survive this in a substantial number. This suggests a strong selective pressure from predators equipped with well-skeletonised oral apparatuses able to crush mineralized body covers of their prey. Possibly, these were some of the associated conodonts of appropriate size and co-evolving towards their ability to crush more and more resistant cuticle. Less likely candidates for durophagy are endoceratid or orthoceratid cephalopods. Also the angarocaridids themselves, equipped with robust gnathobases of cephalic appendages, apparently predated on benthic shelly animals.

Conodont P1 elements of ‘Siphonodella’ are the most important guide fossils for the Tournaisian and topmost Famennian. Hypotheses on the origin and evolution of the elictognathid (‘Siphonodella’) clade are based exclusively on the morphology of one pair of elements in the 15 element apparatus, because of difficulties with its reconstruction. An unusually rich sample taken from the Kowala Quarry in the Holy Cross Mountains, dominated by the core elictognathid species ‘S.’ cooperi, enables corroboration of the interpretation by Sandberg et al. (1978) and falsification of some more recent hypotheses. The elements P1 and P2 of ‘S.’ cooperi show a relatively narrow population variability and do not change morphologically in the course of their ontogeny. In contrast, elements S and M profoundly transformed their pattern of denticulation and general shape during growth. Juveniles are relatively underived and rather easily homologized with elements of other polygnathid apparatuses, but adults are of bizarre morphology unlike any other conodonts. Such a pattern of ontogenetic transformation makes it likely that small P2 elements of relatively generalized morphology and mature Dinodus-type S elements associated with P1 elements of ‘S.’ praesulcata in a Kowala sample taken from the topmost Famennian nodular limestone bed, belong together to the same apparatus. No Devonian conodont apparatus is known that could be compared with the highly derived ‘Siphonodella’ as its possible ancestor. Apparently, the elictognathid lineage immigrated to the Rheic Ocean realm from an unknown source near the end of the Devonian.

A block of stromatolitic limestone found on the Angara River shore near Kodinsk, Siberia, derived from the exposed nearby Ust-kut Formation, has yielded a sample of 146 ellesmeroceratid nautiloid specimens. A minor contribution to the fossil assemblage from bellerophontid and hypseloconid molluscs suggests a restricted abnormal salinity environment. The associated shallow-water low diversity assemblage of the conodonts Laurentoscandodus triangularis and Utahconus(?) eurypterus indicates an age close to the Furongian–Tremadocian boundary. Echinoderm sclerites, trilobite carapaces, and hexactinellid sponge spicules were found in another block from the transitional strata between the Ust-kut and overlying terrigenous Iya Formation; these fossils indicate normal marine salinity. The conodont L. triangularis is there associated with Semiacontiodus iowensis and Cordylodus angulatus. This means that the stromatolitic strata with cephalopods are older than the early Tremadocian C. angulatus Zone but not older than the Furongian C. proavus Zone. The sample of nautiloid specimens extracted from the block shows an unimodal variability in respect to all recognizable aspects of their morphology. The material is probably conspecific with the poorly known Ruthenoceras elongatum from the same strata and region.

The Holy Cross Mts. in southern Poland are generally believed to be split by a tectonic dislocation into two separate parts, a NE one being a part of the Baltic Craton and a SW part belonging to the Małopolska Terrane of a complex geotectonic history connected with the Trans-European Suture Zone (Tornquist Lineament). Unexpectedly, conodont assemblages of earliest Middle Ordovician (early Darriwilian) age from Pobroszyn in the northeastern Łysogóry region and from Szumsko in the southwestern Kielce region show virtually identical species composition. One of the dominant species both in Pobroszyn and Szumsko, Trapezognathus pectinatus sp. n., characterized by denticulated M elements, occurs elsewhere only on the northern margin of Gondwana. Separation of the Małopolska microcontinent from Baltica continued after the disappearance of Trapezognathus and an apparently allopatric speciation process was initiated by a population of Baltoniodus. Also in this case, denticulation developed in the M elements of the apparatus but the process of speciation of B. norrlandicus denticulatus ssp. n. was truncated by re-appearance of the Baltic lineage of Baltoniodus. Later conodont faunas from the region are of Baltic affinities, but remain distinct in showing a relatively high contribution from exotic species of Sagittodontina, Phragmodus, and Complexodus. The periodic North American Midcontinent tropical influences observable in the Baltic region did not reach the Holy Cross Mts. The Ordovician conodont faunas from the Holy Cross Mts. can be fit into a transect extending from Baltica to Gondwana, with several intermediate terranes. This new evidence disproves the long-held concept that the Łysogóry and Kielce regions had separate early Palaeozoic fates and that the Małopolska Terrane was unified with Baltica already in the earliest Ordovician. The Trans-European Suture Zone truly marks the presence of a wide Tornquist Sea in the early Palaeozoic.

Quantitative data on molluscan larval conch fossil assemblages of ages ranging from the Ordovician (Argentina and the Baltic region), through Silurian (Austria), Devonian (Poland) to Carboniferous (Texas) supplement knowledge of early planktonic gastropods communities transformations. They show that larval shells of the bilaterally symmetrical bellerophontids and dextrally coiled gastropods with a hook-like straight apical portion of the first whorl initially dominated. Their relative frequency, as well as that of the sinistrally coiled 'paragastropods', diminished during the Ordovician and Silurian to virtually disappear in the Late Devonian and Early Carboniferous. Already during the Ordovician, diversity of larvae with gently loosely coiled first whorl increased, to be replaced then with more and more tightly coiled forms. Both the aperture constrictions and mortality peaks, probably connected with hatching and metamorphosis, indicate that the Ordovician protoconchs with hook-like first coil represent both the stage of an embryo developing within the egg envelope and a planktonic larva. The similarity of the straight apex to larval conchs of hyoliths and advanced thecosome pteropods is superficial, as these were not homologous stages in early development.

The latest Frasnian and earliest Famennian conodont assemblages at the Si Phai section in northernmost Vietnam are similar to those from coeval strata in Europe, but their taxonomic diversity is significantly lower and the order of species appearances is different. Unlike most other localities, where. Palmatolepis' linguiformis is a very late Frasnian species preceding Klapperilepis ultima, it emerges much earlier at Si Phai, already co-occurring with Ancyrodella lobata. Its contribution to the assemblage is there many times higher than elsewhere. This allows tentative apparatus reconstruction proving its congenerity with Manticolepis rhenana, which at Si Phai occurs only in the lowermost portion of the M. linguiformis range. Another peculiar aspect of this Vietnamese section is the abundance of Avignathus in its lower part. In a subsequent sudden change of apparently ecological nature, a diverse set of polygnathids Ctenopolygnathus and Poly gnathus species followed by Klapperilepis ultima enriched the assemblage. The second dramatic faunal exchange event resulted in the disappearance of all the palmatolepidids except for K. ultima. The Si Phai conodont species succession does not differ from those of other regions of the world in that both the first and last occurrences were caused by ecological changes that, apart of this terminal Frasnian event, are not necessarily of global extend. The widely held assumption that most changes in distribution of conodonts were synchronous may not be true. A truly reliable age correlation should not be based on ecologically controlled appearances and disappearances but on well-documented evolutionary transitions. Unfortunately, evolutionary origin of no one of the palmatolepidid species occurring in Si Phai (with possible exception of Manticolepis winchelli) has been determined elsewhere. This makes the probably phyletic succession of Ancyrodella chronospecies a more reliable tool for age correlation.

Around the Ediacaran-Cambrian transition, about 540 million years ago, marine organisms began to dig in the sediment that has resulted in its better ventilation and further expansion of infaunal life. Few vertical infaunal burrows are known from the Precambrian and they are usually attributed to sea anemones. Here we show that the enigmatic Ediacaran petalonamean 'sea pens' were able to penetrate sediment for more than one centimetre depth while anchoring the body in the microbial mat. Their growth, as evidenced by numerous well-preserved basal discs from the late Ediacaran Lomoziv Member of the Mohyliv Formation in Podolia, Ukraine, was under control of rhythmic sedimentation events and periodic microbial mat development. Size frequency distribution in classes of both the final disc size and growth retention stages show that their size increase was stepwise. Each discrete stage corresponds to deposition of a thin sediment layer and development of the microbial mat at its top. Podolia was located near the South Pole in the Ediacaran (Vendian) and such rhythmic sedimentation was probably connected with the local climate seasonality.

Serially arranged sets of eight septa-like structures occur in the basal part of phosphatic tubes of Sphenothallus from the early Ordovician (early Floian) Fenxiang Formation in Hubei Province of China. They are similar in shape, location and number, to cusps in chitinous tubes of extant coronate scyphozoan polyps, which supports the widely accepted cnidarian affinity of this problematic fossil. However, unlike the recent Medusozoa, the tubes of Sphenothallus are flattened at later stages of development, showing biradial symmetry. Moreover, the septa (cusps) in Sphenothallus are obliquely arranged, which introduces a bilateral component to the tube symmetry. This makes Sphenothallus similar to the Early Cambrian Paiutitubulites, having similar septa but with even more apparent bilateral disposition. Biradial symmetry also characterizes the Early Cambrian tubular fossil Hexaconularia, showing a similarity to the conulariids. However, instead of being strictly tetraradial like conulariids, Hexaconularia shows hexaradial symmetry superimposed on the biradial one. A conulariid with a smooth test showing signs of the origami' plicated closure of the aperture found in the Fenxiang Formation supports the idea that tetraradial symmetry of conulariids resulted from geometrical constrains connected with this kind of closure. Its minute basal attachment surface makes it likely that the holdfasts characterizing Sphenothallus and advanced conulariids are secondary features. This concurs with the lack of any such holdfast in the earliest Cambrian Torellella, as well as in the possibly related Olivooides and Quadrapyrgites. Bilaterally arranged internal structures in polyps representing probably the oldest medusozoans support the suggestions based on developmental evidence that the ancestor of cnidarians also was a bilaterally symmetrical animal. This is one more example of fossil data that strictly fit the molecular phylogenetic evidence but not necessarily morphology-based zoological interpretations.

The fossil record of the anatomical evolution of the human lineage shows that it was very slow and gradual. While changing their habitat from a primeval forest to the unpredictable environment of savannah, our animal ancestors had to change their ecological strategy. As a result, fertility increased, childcare was prolonged, and sedentary family life developed. A hormonal mechanism of filial and sexual imprinting supported these changes by strengthening emotional family ties. This means that such aspects of human biology as sexual behaviour, family love, herd instinct, and feeling of ownership are inherited after our animal ancestors and have a very ancient evolutionary history. The human brain size increase does not necessarily express the development of intellectual abilities but is rather a thermoregulatory mechanism connected with persistence hunting. The intellectual potential of the large brain emerged long after its evolution had been completed. A powerful tool for scientific interpretations of this paradox is offered by the application of the Darwinian way of reasoning to the evolution of human culture, resulting in the selection of ideas. Cultural evolution is cumulative, and some institutions invented by this process may partially liberate humans from the limitations of their biological heritage.