Surface Ornamentation Research Articles

Ancestral state reconstruction reveals extensive homoplasy in nutlet characters of Cynoglossinae (Boraginaceae, subfam. Cynoglossoideae, tribe Cynoglosseae)

Recent phylogenetic studies have challenged the traditional classification of the subtribe Cynoglossinae, which was based on nutlet characteristics. To investigate the evolution of fruit traits related to dispersal modes in this complex group, we conducted a study using scanning electron microscopy to examine 28 taxa representing all previously recognized lineages of the subtribe. Cynoglossinae displays four main types of nutlets: marginate, emarginate, flat wing, and incurved wing. Our findings reveal the arrangement of glochids and their structure, including the number of apical hooks, and their surface ornamentation is highly variable both across and within these four main types. We reconstructed the phylogenetic tree with four main clades (i.e., Clades I–IV) using Maximum likelihood analysis. In addition, we mapped four nutlet traits (i.e., nutlet margin, nutlet glochid, glochid sculpture, and glochid hooks) associated with different dispersal modes using ancestral state reconstruction analysis. The ancestor of subtribe Cynoglossinae was inferred to have marginate and glochidiate nutlets, with glochids externally provided with complex spiny tubercles and bearing at least four hooks at the tip as well as epizoochory dispersal mode. These ancestral states have been retained in Clade II (East Asian-Australian-African Cynoglossum-Lindelofia clade) and Clade III (Mediterranean-Asian Cynoglossum-Solenanthus-Trachelanthus clade), with several independent shifts to emarginate fruits. Transitions from marginate to wide-winged nutlets have occurred at least four independent times, facilitating wind-assisted dispersal in Clade I (Microparacaryum clade), Clade IV (Paracaryum-Mattiastrum-Rindera clade), Rindera tetraspis, and Mattiastrum crista-galli (both belonging to Clade III), where a transition from tuberculate to papillate surface has also occurred.

Leopoldia buseana (Asparagaceae, Scilloideae), a new species from southwestern Anatolia

Leopoldia buseana Yıldırım (Asparagaceae) is described as a new species to science. It is endemic to the western Anatolia region of Türkiye. Leopoldia buseana is only known from Muğla Province. The new species is morphologically similar to L. muglaensis, L. elmasii, and L. weissii. Diagnostic morphological characters are discussed and compared with those related taxa. Leopoldia buseana is easily distinguished from related species by its distinctly longer inflorescence, the number of fertile and sterile flowers, mauve to bluish-mauve buds and early stage of fertile flowers, flat or sometimes slightly channeled and broader leaves, and the seed surface ornamentation. Diagnostic characters, a comprehensive description, photographs, and a distribution map are provided.

Grass pollen surface ornamentation is diverse across the phylogeny: Evidence from northern South America and the global literature

AbstractThe grasses are one of the most diverse plant families on Earth. However, their classification and evolutionary history are obscured by their pollen stenopalynous (similar) morphology. A combination of high‐resolution imaging of pollen surface ornamentation and computational analysis has previously been proposed as a promising tool to classify grass taxonomic boundaries. In this study, we test this hypothesis by studying Poaceae pollen across the phylogeny from plants collected in northern South America and also from published literature across the globe. We assessed if morphotypes that we establish using descriptive terminology are supported by computational analysis, if they vary along six (a)biotic variables and vary across the phylogeny. Based on this analysis, we constructed a reference framework for pollen surface ornamentation morphotypes. Our results showed that there is a wide variation of grass pollen surface ornamentation. We identified nine new and confirmed six known morphotypes, establishing a data set for 223 species (243 individual plant specimens) that represent 11 subfamilies. Computational analysis showed that our morphotypes are well‐supported by two quantitative features of pollen sculptural elements (size and density). The specific data set and mapping of the phylogeny confirmed that pollen morphological sculpture is unrelated to (a)biotic variables and is diverse across the phylogeny.

Two new species of Cerviniella Smirnov, 1946 (Copepoda, Harpacticoida, Aegisthidae) from the Yellow Sea, Korea.

Two new species, Cerviniellabisegmentasp. nov. and C.permixtasp. nov., are described in detail with illustrations based on females from the Korean Yellow Sea. These species lacking the fourth leg endopod belong to the mirabilipes group, one of two species groups within the genus Cerviniella Smirnov, 1946. Both species can be distinguished from each other by the surface ornamentation of the cephalothorax, shape of the rostrum tip, antennule segments, armature formula of thoracic legs 1-4, and length ratio of the caudal rami. Cerviniellabisegmentasp. nov. is characterized by a short caudal ramus and a two-segmented antennary exopod, which are unique within the genus. Cerviniellapermixtasp. nov. differs from other congeners of the mirabilipes group by the seven-segmented antennule, the armature formulae of the exopod of the antenna and thoracic legs 1-4, and the modified apical inner element of the second endopodal segment of the second leg. The present study is the first to identify the genus Cerviniella in Korean waters, resulting in extension of its distribution area to East Asia.

A SCANNING ELECTRON MICROSCOPY STUDY OF POLLEN GRAINS

A simple, quick and non-destructive method of preparing fresh pollen grains for scanning electron microscopy (SEM) studies was used in this investigation. The pollen grains of seven taxa belonging to seven families were studied six were dicots, namely Delonix regia, Helianthus annuus, Justicia spicigera,Kigeliaafricana,Lagerstroemia speciosaand Portulaca umbraticola,and one a monocotHymenocallis littoralis. Fresh pollen grains were dehydrated in acidified 2, 2-dimethoxypropane (DMP) followed by criticalpoint drying in carbon dioxide (CO2). In the preliminary study the acidified DMP treated pollen grains were mounted in glycerine and observed under the light microscope. The DMP direct method preserves the original shape of the pollen grains and dissolves the pollen coat thereby enabling observation of the surface ornamentation of the exine. The high magnifications of the SEM provided detailed information about the fine structure or micromorphology of the pollen surface. In the taxa studied the pollen are aperturate and are shed as monads.Among the taxa studied, P.umbraticola was apolar, H.littoralis was heteropolar,and the remaining five were isopolar. The exine was reticulate in D. regia, H.littoralis, J.spicigera, and K.africana echinate in H. annuusandP.umbraticola andfossulate, perforate in L. speciosa.

Unveiling the intricacies of Amaranthaceous pollen diversity: Advancing ultra sculpture analysis through LM and SEM.

Microscopic techniques can be applied to solve taxonomic problems in the field of plant systematic and are extremely versatile in nature. This study was focused on the new approaches to visualizing the imaging, tool to cover the micro-structural techniques applied to the pollen study of Amaranthaceae floral biology. In this detailed study, we used light microscopy and scanning electron microscopy to examine the shape and changes in pollen of 16 types of Amaranthaceae plants from the salty arid zone of Riyadh Saudi Arabia. We observed subtle variations among the studied species through meticulous examination of morpho-palynological features such as symmetry, size, shape, pore ornamentation, and exine characteristics. The pollen grains were round and had rough or prickly outer coverings. They had different numbers of tiny pores; some were slightly sunken. These findings were utilized to develop a pollen taxonomy key, facilitating accurate identification and classification of Amaranthaceous species. Our results shed light on the taxonomic significance of pollen morphology for species differentiation within the Amaranthaceae family. Furthermore, this study provides valuable insights into the influence of geographical and ecological factors on pollen diversity and evolution. This study of pollen imaging visualization of Amaranthaceous species contributes to the opportunity for taxonomic evaluation and fill knowledge gaps in studies of Amaranthaceous flora identification using classical microscopic taxonomic tools for their accurate identification. RESEARCH HIGHLIGHTS: The pollen characters of selected Amaranthaceae species were visualized using scanning electron microscopy to observe sculptural wall pattern. The comprehensive Amaranthaceous pollen examination approach allowed us to accurately identify their micromorphology. This high-resolution imaging technique provided detailed insights into the surface structures and ornamentation of the pollen grains.

Pyritization and Preservation Model of Chrysophyte Cyst Fossils in Shales during the Triassic Carnian Pluvial Episode, Ordos Basin, China: Evidence from Cyclostratigraphy, Radiometric Dating and Geochemical Analyses

Chrysophyte cyst fossils were widely pyritized and preserved in black shales from the seventh member (Ch7 Mbr) of the Yanchang Formation in the Ordos Basin. The age, pyritization, and preservation model of these fossils have not been studied previously. In this study, the astronomical orbital cycles of the Ch7 Mbr were determined based on the gamma ray series of the Yan56 and Zhen 421 wells. An astronomical time scale (ATS) analysis revealed that the depositional duration of Ch7 Mbr was approximately 5 Ma. According to the 206Pb/238U radiometric dating of zircons using laser ablation inductively coupled plasma mass spectrometry (La-ICP-MS), the tuffs at the bottom of Ch7 Mbr were crystallized at 234 Ma, which served as a geological anchor. The ages of three submembers in Ch7 Mbr were estimated at 234.0–232.4 Ma, 232.4–230.8 Ma, and 230.8–229.1 Ma based on ATS analysis. In addition, chrysophyte cyst fossils were well preserved by pyritization in the Ch7 Mbr black shales. There were six types of microscopic morphologies with different pores, collars, and surface ornamentation under scanning electron microscopy (SEM). The age of the chrysophyte cyst fossils was at least 233.6 Ma in the Triassic Carnian Pluvial Episode (CPE) based on the 405 kyr tuned ATS. Moreover, the paleoredox conditions in Ch7 Mbr were reconstructed, and a preservation model of chrysophyte cyst fossils was established based on geochemical analyses. Fossil pyritization was caused by bacterial sulfate reduction near the water-sediment interface under suboxic to anoxic environmental conditions. Pyritization was initiated on the walls of the chrysophyte cysts by the formation of microcrystalline pyrite. Because of the gradual pyritization of the chrysophyte cyst wall, the organic matter in the interior of the fossil was well preserved.

Orthoseira groenlandica sp. nov., a new aerophilic diatom (Orthoseirales, Bacillariophyta) species from Greenland

During the survey of the moss-inhabiting diatoms in samples from Greenland, an unknown Orthoseira taxon was observed that was originally identified as O. roeseana but differed from the recently published lectotype population of the latter. Comparison with all known Orthoseira taxa worldwide showed that the unknown taxon represented a new species that is described as O. groenlandica, sp. nov. based on detailed light and scanning electron microscopy. The combination of the unique, rather chaotic valve face and mantle surface ornamentation, the absence of caverns and marginal pore fields, the presence of robust, short spines, and the absence of chain-like colonies has not been observed so far in any known Orthoseira species. The morphology of the new species is discussed comparing it with the morphology of all other Orthoseira species worldwide by carefully analysing the different morphological features observed so far in members of the genus Orthoseira. Brief notes on the ecology of the sample where the new species was found are added.

Pollen morphology and variability among the wild Cannabis sativa L. from the western Himalaya, India

The present study aimed to examine the intraspecific variation in pollen traits of genus Cannabis from Western Himalaya, India. A total of 1650 pollen grains from 55 accessions collected from an altitudinal range between 259 and 2751 m a.s.l from the western Himalayas, India were analyzed by (LM) light microscopy and (SEM) Scanning Electron Microscopy. Six quantitative characters, i.e., length of the polar axis (P), length of equatorial axis (E), exine thickness (Ex), number of granules (Ng), pore diameter (Pd), and P/E ratio were studied. Pollen grains of maximum accessions were tricolpate while pollen grains of three accessions i.e., CAN17, CAN25 and CAN31 were tetraporate. Majority of the pollen grains were prolate spheroidal (83.64%) whereas 1.82% was spheroidal. PCA indicated that the first four components account for 69.9% of the total variability. PC1 attribute 34.41% of the variability with equatorial diameter being the significant variable, whereas PC2 contributed 19.57% variability having length of polar axis (P) and shape class (P/E) as the significant variables. PC3 contributed 20.1% of the total variability with PE and number of granules being the significant variables. Pollen size, aperture number, and surface ornamentation may prove useful in species discrimination. This current study gives a first-hand report on the palynological variation of wild Cannabis populations of the Western Himalaya, India.

Seed morphology of Hypericum(Hypericaceae)in China and its taxonomic significance.

The seed morphology of 40 taxa within the genus Hypericum (Hypericaceae) from China, representing 9 sections of the genus, was examined using both Light and Scanning Electron Microscopy to evaluate the taxonomic relevance of macro- and micro-morphological features. Details articulating variation in seed size, color, shape, appendages, and seed coat ornamentation are described, illustrated, and compared, and their taxonomic importance is discussed. Seeds were generally brown in color and cylindric-ellipsoid to prolonged cylindric in shape. Seed size displayed wide variation, ranging from 0.37-1.91 mm in length and 0.12-0.75 mm in width. Seed appendages were observed as a characteristic morphological feature. Seed surface ornamentation has high phenotypic plasticity, and four types (reticulate, foveolate, papillose, and ribbed) can be recognized. In general, seed color and shape have limited taxonomic significance. However, some other features represent informative characters that can be used efficiently in distinguishing the studied taxa at the section and/or species levels. The findings illustrate that considerable taxonomic knowledge can be obtained by investigating the seed features of Hypericum, and the use of Scanning Electron Microscopy can reveal inconspicuous morphological affinities among species and play a role in taxonomic and systematic studies of the genus Hypericum. RESEARCH HIGHLIGHTS: Macro- and micro-morphological features of seeds of 40 Hypericum taxa from China were examined using Light and Scanning Electron Microscopy, providing the first broad study regarding seed morphology for Hypericum from China. Details and variations of seed size, shape, color, surface ornamentation, and appendages are fully presented. Seed features and their variation have important taxonomic significance at the section and/or species levels within Hypericum.

Comprehensive leaf and pistil micromorphology and its taxonomic value in the Korean Luzula species

Micromorphological characteristics provide important diagnostic criteria for differentiating plant groups and have thus been widely used to better understand the taxonomic significance of morphologically complex species. A comprehensive leaf and pistil micromorphological study of the Korean woodrush was performed using light and scanning electron microscopy to determine whether comparisons of these provide systematically informative traits. All six examined Korean Luzula species belonged to two subgenera, Luzula (L. capitata, L. multiflora and L. pallescens) and Pterodes (L. odaesanensis, L. rufescens and L. plumosa), and had hypostomatic leaves, with paracytic stomatal complexes found only on the abaxial surface. The epidermal surface could be divided into two types: verrcuate or scabrate on both abaxial and adaxial leaves. Guard cell length was an important trait for subgeneric identification in Korean Luzula, but highly variable among species, ranging from 23.02 μm in L. capitata to 63.75 μm in L. odaesanensis, in which the size variations might be influenced by different environmental conditions. The occurrence of abnormal stomatal complexes in the Korean Luzula species was reported here for the first time, which could be an adaptation to various environmental factors. We also report a detailed description of the pistil microstructure of Korean woodrush. Despite similar pistil surface ornamentation, the micromorphological features described in this study provide valuable information for developing further systematic context in the Korean Luzula species.

Comparative anatomy and achene micromorphology assessment of two Cousinia Cass. (Asteraceae) species in view of taxonomy

Comparative anatomy and achene micromorphology assessment of two Cousinia Cass. (Asteraceae) 
 species in view of taxonomy
 Deniz ULUKUŞ 1, Osman TUGAY 2
 ORCID: 0000-0002-9627-5492; 0000-0003-3980-7648
 
 1 Department of Biotechnology, Faculty of Sciences, Selçuk University, Konya, Turkey
 2 Department of Pharmaceutical Botany, Faculty of Pharmacy, Selçuk University, Konya, Turkey 
 
 Abstract
 Cousinia is a member of the monophyletic tribe Cardueae, which is traditionally subdivided into four taxonomic groups; however, the rank and boundaries of these taxa are highly controversial. The purpose of this study was to contribute to the genus taxonomy by determining the comparative anatomical and achene micromorphological features of C. aintabensis Boiss. & Hausskn. and C. birecikensis Hub.-Mor. that are morphologically similar to each other. In anatomical studies, stem, leaf, and midrib features were determined. Paraffin embedding, microtome sectioning, and safranin-fast green staining were used for the samples. The obtained sections were photographed, and the leaf, stem, and midrib characters were measured. The importance of anatomical characters between species was determined by applying Independent sample T-test test to quantitative characters. In addition, box plot and heatmap analyses of the studied species were carried out. Our results showed that the stem epidermis, inner sclerenchyma and phloem layer; For leaves; lower and upper epidermis mesophyll thickness, palisade parenchyma; In midrib; number of vascular bundles, collenchyma, and phloem are important characters that can be used in the differentiation of species. SEM microscope was used for achene micromorphological examinations. C. aintabensis achene surface ornamentation is identified as striate-retipylate. It was observed that C. birecikensis had striate and irregular reticulate-faveolate surface ornamentation.
 
 Keywords: Asteraceae, Anatomy, Cousinia, micromorphology, Türkiye

In situ growth of modern oncoids from Salado river, Salar de la Laguna Verde Complex, Argentina

This study explores a modern oncoids deposit in the Salado river, a high-altitude brackish river in the Puna region of Catamarca province, Argentina. This contribution focuses on oncoids features at macro-, meso-, and microscale as tools to provide insights into mechanisms of development and environmental information. Based on a detailed sedimentological, petrographic, and biodiversity analyses, it is suggested a primarily in situ growth of the oncoids, without being regularly overturned. Four key features are considered supporting this interpretation: (1) oncoids are placed in a stable position being partially buried in the substrate; (2) the existence of an attached thin biofilm outlining the contact of oncoids with the substrate which indicate their stable position during growth, at least for a certain period; (3) the carbonate cortexes display an uneven thickness being the uppers up to 1–2 times thicker than the lowers, suggesting asymmetrical growth during oncoids development; (4) well-preserved surface ornamentation (e.g., pustules) on the upper side in contrast with smooth bottom cortexes in contact with the substrate. Additionally, an integral analysis of the geochemistry of the river water and stables isotopes values from carbonate oncoids, suggest that water mixing (e.g., thermal and fresh-water inputs), high evaporation rates, and CO2 degassing are the main processes that promote calcite precipitation and therefore oncoids growth. Also, the role of bacteria and diatoms on the microstructure development as well as their possible implications on carbonate precipitation is discussed.

Multigene phylogeny reveals a cryptic diversity in the genus Dinobryon (Chrysophyceae) with integrative description of five new species.

The genus Dinobryon is one of the most recognizable chrysophyte genera, characterized by dendroid colonies with a biflagellate inside each cellulosic lorica. The representative forms of lorica are cylindrical, conical, vase, or funnel shaped, with undulation on the lorica wall. Traditionally, the morphological characteristics of the lorica and the colony organization have been used for the delimitation of Dinobryon species. To understand the taxonomy and phylogeny of colonial Dinobryon species, we performed molecular and morphological studies using 39 unialgal cultures and 46 single colony isolations from environmental specimens collected in Korea. We used a nuclear internal transcript spacer (ITS1-5.8S-ITS2) to find the genetic diversity of Dinobryon from environmental samples and a combined dataset from six gene sequences (nuclear SSU and LSU rRNA, plastid LSU rRNA, rbcL and psaA, and mitochondrial CO1 genes) for phylogenetic analysis. We found 15 different lineages based on the genetic diversity of the nuclear ITS sequences. The phylogenetic tree of the colonial species based on the combined multigene dataset were divided into 18 subclades, including five new species, each with unique molecular signatures for the E23-5 helix of the V4 region in the nuclear SSU rRNA and the E11-1 helix of D7b, and the E20-1 helix of D8 regions in the nuclear LSU rRNA. Morphological studies were focused on lorica dimension and shape, and stomatocyst morphology. The Dinobryon species showed similarities or differences in lorica morphologies between and within species, and also differences in lorica size between culture and environmental samples. Five Dinobryon species formed distinctive stomatocysts, their stomatocyst morphologies, including collar structure, surface ornamentation, and cyst shape, showed unique characteristics in each species and were useful for identification. Here, we propose five new species based on morphological and molecular evidences: D. cylindricollarium, D. exstoundulatum, D. inclinatum, D. similis, and D. spinum.

Skeletal variation of the stem turtle Naomichelys speciosa (Testudinata: Helochelydridae): insights from a new specimen from the Lower Cretaceous Cloverly Formation of Montana

Specimens of Naomichelys speciosa are typically represented by fragmentary shell elements that offer little morphological information beyond surface ornamentation, and only a single mostly complete specimen has been described in detail. Here, we describe a second relatively complete specimen of N. speciosa from the Cloverly Formation of Montana. This specimen provides new information on the morphology of damaged or missing skeletal elements from previously described specimens including costal I, the peripheral series, plastral bridge, cervical vertebrae, and femur. New diagnostic features of N. speciosa include the presence of supernumerary pleural scutes on costal I, the absence of intergular scutes, and the variable presence of central plastral fontanelle. Additionally, this specimen offers insight into intraspecific variation within N. speciosa such as, the presence/absence of the central plastral fontanelle and the relative size/shape of the entoplastron and entoplastral scute.

Burrow systems of modern subterranean rodents (Ctenomyidae): key neoichnologic features and recognition of fossil examples

This study is aimed to identify the distinctive ichnologic features of burrow systems of two ctenomyid species of extant solitary and subterranean rodents (Ctenomys azarae and C. talarum occidentalis) from La Pampa Province (Argentina). A total of 12 active burrows from different biogeographic provinces were cast with polyurethane foam, then excavated and the entire system was mapped. Ctenomyid burrow systems are shallow (average depth 0.30 m), branched, and subhorizontal with several plugged entrances, having a main tunnel and secondary ones arranged in a single level. Curved length, tortuosity, fractal dimension branching angles, and the scarcity or absence of chambers are similar in both species. The average horizontal diameter is 66 mm, the burrow cross-section is subcircular to vertical elliptical, and entrance ramps slope at an average of 22°. Surface ornamentation in the form of sets of three curved claw traces composing a chevron pattern is dominant. Ctenomys azarae is distinguished from C. talarum occidentalis by the presence of food caches and wider sets of claw traces. Ctenomyidae burrows are easily distinguished from those of Octodontidae and Caviidae using the relative diameter index. The outlined criteria are applied to identify fossil examples of Late Miocene-Holocene ctenomyid burrows.

Favocassidulina Tuberculata N. SP., A New Benthic Foraminifer from the Portuguese Continental Slope

Abstract Favocassidulina tuberculata, a new benthic foraminiferal species from Integrated Ocean Drilling Program Site U1391 drilled on the southwest Portuguese continental slope, is described. This new species has a slit-shaped apertural opening oblique to the test periphery instead of paralleling the periphery as the type species Favocassidulina favus (Brady) does. And more notably, this species possesses a test surface ornamented with tubercles, quite different from the coarse honeycomb wall structure of F. favus and the finely irregular cancellate surface ornamentation of other Favocassidulina species. This paper for the first time reports the presence of the genus Favocassidulina in the Atlantic Ocean.

NEOICHNOLOGY OF ARMADILLOS: KEYS FOR THE PALEOECOLOGICAL AND BEHAVIORAL INTERPRETATION OF FOSSIL TETRAPOD BURROWS

ABSTRACTThis study is based on the analysis of burrow casts of three species of armadillos from central Argentina: Chaetophractus villosus, Chaetophractus vellerosus, and Zaedyus pichiy (Chlamyphoridae: Euphractinae). The aim of this work was to identify key ichnologic signatures of Euphractinae armadillo burrows for application to the paleoecological and behavioral interpretation of fossil examples. A total of 15 active burrows from different biogeographic provinces were casted with polyurethane foam and then excavated. About two hundred uncasted burrows and foraging pits were also measured at the same localities. Euphractinae burrows are clearly distinguished from Chlamyphorinae burrows by its filling, surface ornamentation, and size. It is suggested that fossil armadillo (Euphractinae) burrows would be characterized by a single ramp with one entrance and massive or laminated fill, horizontal diameter larger than 100 mm, strongly marked sets of three claw traces that are arranged oblique to the ramp axis, and absence of feces or plant remains. The distinctive surface ornamentation present in the casted burrows is tentatively linked to a particular excavation mechanism involving rotation of the body along the antero-posterior axis. Burrow systems with a chamber are interpreted as permanent burrows, whereas those lacking chamber are considered as temporary/shelter burrows. Armadillo burrow systems (either temporary or permanent) are longer, less inclined, and have lower relative diameter indices (RDI) than armadillo foraging pits. Euphractinae burrows are linked to producers with solitary, fossorial, opportunistic omnivorous habits that excavate several burrows during their lives. They are left open after abandonment, and preferably located in xeric shrub lands and grasslands. The described morphological features of the burrows systems can be useful for the interpretation of fossil (post-Eocene) burrows.

Paleoecological and paleobiogeographical inferences of the Paleocene ostracods from Sinai, Egypt

The present study aims to detect the paleoecology and paleobiogeography of the Paleocene ostracods from Sinai, Egypt. In order to reach our goals, the Paleocene rocks were examined in four outcrops (El Dokh, El Qussaima, Matulla, and Ekma sections) from Sinai, Egypt. The recognized rock units include Dakhla Formation (at the base) and Tarawan Formation (at the top). The investigation of the ostracod fauna yielded 49 species and subspecies, which enabled the recognition of one Paleocene biozone, Mauritsina teiskotensis - Ordoniya ordoniya Zone. The Early and Middle Paleocene have diverse assemblages, while the Late Paleocene showed a rarity of ostracods. Based on the shape of the carapaces and the surface ornamentation, four ostracod morphogroups were recognized. Morphogroup 4 is the most common group in all the studied sections. The structure of ostracod assemblages (abundance, richness and the morphogroups) besides the lithology pointed out to middle - outer neritic depositional environment for the studied Paleocene sections. The identified species have a wide geographic range, extending from West Africa, North africa to the Middle East. The paleobiogeographic framework is carried out with the aid of multivariate analyses. The suggested matrix consists of 25 ostracod species from 10 countries, including Egypt, Libya, Tunisia, Algeria, Jordan, Israel, Senegal, Ivory Coast, Niger and Mali. The outcomes of the Q-mode cluster analysis indicate that the selected countries may be categorized into three provinces, North Africa (Libya, Algeria, Tunisia and Egypt), West Africa (Senegal, Mali, Ivory Coast and Niger), and Middle East (Israel and Jordan). The similarity of ostracod assemblages between North Africa, including Egypt, with that of Jordan and Israel, suggests the migration and exchange through the southern Tethyan coast. The common deep marine species between North and West Africa may be migrated along the West African coast on the Atlantic Ocean, while shallow species migrated through the trans-Saharan seaway.

A new sturgeon from the Upper Cretaceous Horseshoe Canyon Formation in central Alberta, Canada

The posterior portion of a sturgeon skull preserved in a nodule was recovered from the latest Campanian sediments of the Horseshoe Canyon Formation in the city of Edmonton, Alberta, Canada. It is described here as a new genus and species of Acipenseriformes. The skull represents an individual of at least 2 meters in total length. This species is of particular interest because different bones of the skull show a surface ornamentation with different patterns; the clavicle has large pits, the dermal skull bones have smaller pits and radiating ridges, and the subopercle shows fine radiating ridges. The new taxon, here named †Boreiosturion labyrinthicus, can be confidently included in the extant family Acipenseridae but a phylogenetic analysis does not further resolve relationships. This fossil is the first documentation of sturgeon in the latest Campanian of North America, and bridges the gap between the mid-Campanian assemblage of Dinosaur Park and the late Maastrichtian material from the Hell Creek Formation.