Conellae, enigmatic structures on cephalopod shells—shapes, distribution, and formation

Conellae, enigmatic cone-shaped structures which can be found on the surface of internal moulds of cephalopod shells (predominantly of ammonoids), are regarded herein as the product of remote (biologically induced) biomineralization formed in closed-off cavities during lifetime and might be primarily composed of vaterite, aragonite, or calcite. To date conellae have been interpreted in many different ways: (i) as organisms (gastropods, cirriped crustaceans, or disciniscid brachiopods), (ii) pre-diagenetic syn vivo features, i.e., biologically controlled or induced, the product of remote biomineralization, (iii) and diagenetic, i.e., abiogenic origin and post-mortem. The proposed processes of conellae formation seem insufficient to explain conellae related phenomena. Further, their assumed primary aragonitic or calcitic mineralogy are reviewed and based on new material critically assessed. The stratigraphic range of conellae extends from the Middle Ordovician and probably to modern Nautilus. Predominantly, conellae can be found on internal moulds along the keel, ribs or nodes, umbilical shoulder, at the transition between phragmocone and body chamber, and can be associated with repaired scars. However, conellae are also common on the smooth body chambers of large macroconchs of Jurassic ammonites. Conellae, which are located on ammonite body chambers, are filled with the same material found in the body chamber and can contain small burrows, sand grains, or coprolites. Some of these conellae are partially covered with nacreous shell material. Limonitic conellae were also found on the limonitic internal moulds of orthocone nautiloids. Moreover, disciniscid brachiopods found on inoceramid bivalves were re-identified herein as conellae. A short guide for conellae identification has been provided herein

Evolutionary development of the cephalopod arm armature: a review

The cephalopod arm armature is certainly one of the most important morphological innovations responsible for the evolutionary success of the Cephalopoda. New palaeontological discoveries in the recent past afford to review and reassess origin and homology of suckers, sucker rings, hooks, and cirri. Since a priori character state reconstructions are still ambiguous, we suggest and discuss three different evolutionary scenarios. Each of them is based on the following assumptions: (1) Neocoleoidea uniting extant Decabrachia and Octobrachia is monophyletic (= proostracum-bearing coleoids); (2) extinct Belemnitida and Diplobelida are stem decabrachians; (3) proostracum-less coleoids (Hematitida, Donovaniconida, Aulacoceratida) represent stem-neocoleoids; (4) Ammonoidea and Bactritoidea are stem coleoids. We consider a scenario where belemnoid hooks derived from primitive suckers as well-supported. Regarding belemnoid hooks and suckers as homologues implies that belemnoid, oegopsid, and probably ammonoid arm hooks arose through parallel evolution. Our conclusions challenge the widespread opinion, whereupon belemnoid hooks evolved de novo, and instead support earlier ideas formulated by Sigurd von Boletzky

The correct taxon name, authorship, and publication date of extant ten-armed coleoids

A variety of conflicting names with different authorship is available and has been repeatedly cited for living ten-armed coleoid cephalopods. Here, I review the primary literature and show the correct name, authorship, and date for ten-armed coleoids

Geometric morphometrics in ammonoids based on virtual modelling

Linear morphometrics is the most widely applied technique to study the variationof the conch morphology in ammonoids and other ectocochleate cephalopods. However,because this method frequently relies upon a few linear measurements, it lacksthe explanatory power to accurately characterize the shape of the whorl cross-section,which is instead discussed solely in descriptive terms, e.g., elliptical, triangular, or subquadrate.Here, we introduce a landmark-based geometric morphometric approach tostudy ammonoid whorl cross-sections, derived from the regularly used morphometricparameters in cephalopods. This new technique uses virtual modelling to generatesemi-landmark configurations and virtual models of whorl cross-sections. We applied itto study 50 ammonoid specimens belonging to 48 genera exhibiting a wide range ofmorphologies and ages. Results indicate that this new method is appropriate todescribe the shape of ammonoid whorl cross-sections, allowing us to construct a morphospaceshowing several biological patterns (e.g., clustering and homeomorphy), andcomplex morphological transformations that, in some cases, correlate with evolutionarytendencies described by previous authors. Further, this technique can be used togenerate the basic segment required for the elaboration of the virtual models employedin hydrostatic and hydrodynamic studies.Fil: Moron Alfonso, Daniel Andres. Consejo Nacional de Investigaciones Científicas y Técnicas. Oficina de Coordinación Administrativa Ciudad Universitaria. Instituto de Estudios Andinos "Don Pablo Groeber". Universidad de Buenos Aires. Facultad de Ciencias Exactas y Naturales. Instituto de Estudios Andinos "Don Pablo Groeber"; ArgentinaFil: Hoffmann, René. Ruhr Universität Bochum; AlemaniaFil: Cichowolski, Marcela. Consejo Nacional de Investigaciones Científicas y Técnicas. Oficina de Coordinación Administrativa Ciudad Universitaria. Instituto de Estudios Andinos "Don Pablo Groeber". Universidad de Buenos Aires. Facultad de Ciencias Exactas y Naturales. Instituto de Estudios Andinos "Don Pablo Groeber"; Argentin

Special issue: recent advances in Cambrian to modern cephalopod research I

In September 2014, the 9th International Symposium Cephalopods—Present and Past was held at the Universitz of Zurich in combination with the 5th International Coleoid Symposium. Here, give a short account of these two events

Robotic-assisted abdominal aortic surgery: evidence and techniques

In various disciplines, robotic-assisted surgery is a well-proven routine procedure, but have never been established in vascular surgery so far. This review summarizes the results to date of robotic-assisted abdominal aortic surgery (RAAS) in the treatment of aorto-iliac occlusive disease (AIOD) and abdominal aortic aneurysm (AAA). Web-based literature search of robotic-assisted surgical procedures on the abdominal aorta and iliac arteries between 1990 and 2020 including the Cochrane Library, OVID Medline, Embase, and PubMed medical databases. All studies conducting Robotic-assisted surgery were included in the quantitative analysis regarding operative and cross-clamping times, conversion rates, mortality and morbidity within the first 30 days, and in-hospital stay. Case reports and case studies (< 5 patients) were not included. Twenty-four studies were deemed thematically eligible for inclusion; after exclusion of duplicate publications, nine met the inclusion criteria for further analysis. A total of 850 patients who had either abdominal aortic aneurysm or aorto-iliac occlusive disease underwent RAAS. One study of abdominal aortic aneurysm, three of aorto-iliac occlusive disease, and five studies of both disease entities were analyzed quantitatively. For AAA, conversion rates ranged from 13.1 to 20% and perioperative mortality ranged from 0 to 1.6% with in-hospital stay of 7 days. For aorto-iliac occlusive disease, conversion rates ranged from 0 to 20%, and perioperative mortality ranged from 0 to 3.6% with in-hospital stay of 5-8 days. RAAS has been shown to be technically feasible with acceptable short-term outcomes and questionable benefits in terms of in-hospital stay and complication rates. RAAS is currently considered only an outsider procedure. Randomized-controlled trials are indispensable for regular use in vascular surgery as well as a clear approval situation for the vascular sector

Takahashiceras – A new generic name proposed for Takahashia Matsumoto, 1984

We propose Takahashiceras as a replacement name for the pre-occupied Upper Cretaceous ammonite genus Takahashia Matsumoto 1984

Preservation of nautilid soft parts inside and outside the conch interpreted as central nervous system, eyes, and renal concrements from the Lebanese Cenomanian

Nautilid, coleoid and ammonite cephalopods preserving jaws and soft tissue remains are moderately common in the extremely fossiliferous Konservat-Lagerstätte of the Hadjoula, Haqel and Sahel Aalma region, Lebanon. We assume that hundreds of cephalopod fossils from this region with soft-tissues lie in collections worldwide. Here, we describe two specimens of Syrionautilus libanoticus (Cymatoceratidae, Nautilida, Cephalopoda) from the Cenomanian of Hadjoula. Both specimens preserve soft parts, but only one shows an imprint of the conch. The specimen without conch displays a lot of anatomical detail. We homologise the fossilised structures as remains of the digestive tract, the central nervous system, the eyes, and the mantle. Small phosphatic structures in the middle of the body chamber of the specimen with conch are tentatively interpreted as renal concrements (uroliths). The absence of any trace of arms and the hood of the specimen lacking its conch is tentatively interpreted as an indication that this is another leftover fall (pabulite), where a predator lost parts of its prey. Other interpretations such as incomplete scavenging are also conceivable

Dichotomous Impact of Myc on rRNA Gene Activation and Silencing in B Cell Lymphomagenesis

A major transcriptional output of cells is ribosomal RNA (rRNA), synthesized by RNA polymerase I (Pol I) from multicopy rRNA genes (rDNA). Constitutive silencing of an rDNA fraction by promoter CpG methylation contributes to the stabilization of these otherwise highly active loci. In cancers driven by the oncoprotein Myc, excessive Myc directly stimulates rDNA transcription. However, it is not clear when during carcinogenesis this mechanism emerges, and how Myc-driven rDNA activation affects epigenetic silencing. Here, we have used the E&micro;-Myc mouse model to investigate rDNA transcription and epigenetic regulation in Myc-driven B cell lymphomagenesis. We have developed a refined cytometric strategy to isolate B cells from the tumor initiation, promotion, and progression phases, and found a substantial increase of both Myc and rRNA gene expression only in established lymphoma. Surprisingly, promoter CpG methylation and the machinery for rDNA silencing were also strongly up-regulated in the tumor progression state. The data indicate a dichotomous role of oncogenic Myc in rDNA regulation, boosting transcription as well as reinforcing repression of silent repeats, which may provide a novel angle on perturbing Myc function in cancer cells

Anatomy and size of Megateuthis, the largest belemnite

Belemnite rostra are very abundant in Mesozoic marine deposits in many regions. Despite this abundance, soft-tissue specimens of belemnites informing about anatomy and proportions of these coleoid cephalopods are extremely rare and limited to a few moderately large genera like Passaloteuthis and Hibolithes. For all other genera, we can make inferences on their body proportions and body as well as mantle length by extrapolating from complete material. We collected data of the proportions of the hard parts of some Jurassic belemnites in order to learn about shared characteristics in their gross anatomy. This knowledge is then applied to the Bajocian genus Megateuthis, which is the largest known belemnite genus worldwide. Our results provide simple ratios that can be used to estimate belemnite body size, where only the rostrum is known