Gerd Geyer

• Dr. rer. nat., apl. Prof.
• University of Wuerzburg

The 28 February 2025 Research Article "A genome-based phylogeny for Mollusca is concordant with fossils and morphology" [1] expands recent phylogenetic studies [2-4] of all extant mollusk classes. Our concern is that an updated geochronology [5] and revised taxonomy of age "calibration" fossils [1] show that all of the Cambrian (ca. 538-487 Ma [5-7...

Examination of Middle Cambrian hyolithidans from the Manuels River Formation of Avalonian southeastern Newfoundland reveals the presence of Nevadotheca tenuistriata (Linnarsson, 1871), two forms identified as Angusticornid? gen. and sp. 1 and Angusticornid? gen. and sp. 2, Tulenicornus gracilior (Matthew, 1895a), as well as four additional, incompl...

Many results of regional geological syntheses counter the Álvaro & Mills (2024; Álvaro, 2021) synthesis of a rift/half-graben depositional regime of Avalonian SE Newfoundland, with all evidence pointing to a persistent strike-slip regime. A long-term (terminal Ediacaran–Ordovician) stratified basin with shallow peritidal bedded limestones that mark...

Many results of regional geological syntheses counter the Álvaro & Mills (2024; Álvaro, 2021) synthesis of a rift/half-graben depositional regime of Avalonian SE Newfoundland, with all evidence pointing to a persistent strike-slip regime. A long-term (terminal Ediacaran–Ordovician) stratified basin with shallow peritidal bedded limestones that mark...

Notostracan branchiopods reported from the Lower Triassic Voltzia Sandstone Lagerst€atte in northeastern France have previously been assigned to Triops cancriformis, making this species the longest persisting animal in earth history. Careful restudy of the splendidly preserved material indicates that the species can be well characterized but repres...

Probably lowermost Wuliuan (mid-Cambrian) rocks in the Franconian Forest compose the Wildenstein Member of the Tannenknock Formation. They include a surprisingly diverse fauna with a characteristic West Gondwanan, Atlas-type trilobite assemblage. The assemblage – hitherto having been inadequately characterised and poorly described – includes Condyl...

Beranek et al.'s (2023) U-Pb detrital zircon work strengthens the Peribaltic, not Perigondwanan, model for the early evolution of Avalo-nia, the largest exotic terrane in the Acadian-Caledonian orogen of NE North America and western Europe. However, their synthesis blurs evidence of the timing of the Ediacaran "Avalonian orogeny" and overlooks the...

Appearance of the Cambrian Evolutionary Fauna is marked by a transition between the Terreneuvian Series (without known, or mineralized, trilobites) and Series 2 (commonly with trilobites) and appearance of more complex ecologic communities. Our new dates show the Terreneuvian–Series 2 (ca. 29 Ma) brackets two thirds of the Cambrian, with ca. 13 Ma...

The Lower Cambrian (Placentian–Branchian Series) of Avalonian southeastern Newfoundland contains one of the most diverse and best-preserved assemblages of Early Cambrian hyoliths from the North American continent. Primary type, topotype and hypotype specimens from the Brigus Formation collected in the late nineteenth and early twentieth centuries a...

High-precision U-Pb zircon ages on SE Newfoundland tuffs now bracket the Avalonian Lower–Middle Cambrian boundary. Upper Lower Cambrian Brigus Formation tuffs yield depositional ages of 507.91 ± 0.07 Ma ( Callavia broeggeri Zone) and 507.67 ± 0.08 Ma and 507.21 ± 0.13 Ma ( Morocconus-Condylopyge eli Assemblage interval). Lower Middle Cambrian Chamb...

Avalonia, the largest terrane of the Appalachian–Caledonian orogen, is best defined by a terminal Ediacaran–Ordovician sedimentary rock-dominated cover sequence (e.g., Rast et al., 1976) unconformable on a largely Mesoproterozoic–early Neoproterozoic basement (e.g., Murphy et al., 2018). Our concerns with Álvaro et al.’s (2022) depositional synthes...

Cambrian volcanic ashes are common in SE Newfoundland, and regional sampling has provided a zircon date sequence that brackets the Avalonian Lower-Middle Cambrian boundary interval faunal succession. The new U-Pb ages from the Brigus Fm. (upper-uppermost Lower Cambrian, Callavia broeggeri Zone-Morocconus-Condylopyge eli Assemblage) and lower Chambe...

The Brèche à Micmacca Member at section Le IX in the Lemdad syncline, located in the southern part of the High Atlas in Morocco, contains a diverse range of helcionelloid molluscs, probable polychaetes, and sclerites from other metazoan groups. This collection, consisting of over 3,000 specimens, complements previously described faunal assemblages...

Exhaustive similarities in terminal Ediacaran–Ordovician cover sequences between tectonic inliers in the Appalachian–Caledonian (A–C) orogen define the Avalonian terrane from coastal northeast North America through southern Britain to Belgium. However, Barr et al. effectively block inclusion of the Mira belt (Mb) in Avalonia by masking a long-docum...

Earth's oldest cephalpods remain Late Cambrian in age. They appeared at the dawn of the Great Ordovician Diversification Interval as early nektic carnivores along with conodonts. A recent report of purported "cephalopods" 30 m.y. older in the Early Cambrian of eastern Newfoundland proves to be incorrect, as the tubular fossils are readily referable...

The lower Palaeozoic succession of central Europe exposed in the Bohemian Massif is a classic area of geology with a long-standing tradition of research dating back to the 18th century. The Ordovician rocks form parts of sections in several units that sit on the Cadomian basement. These sedimentary and volcano-sedimentary fillings of partial depres...

The Deh‐Molla Formation of the Alborz Zone in northern Iran is a key unit to understanding global sea‐level fluctuations, and likely climate changes during the Furongian Epoch. The sedimentological characteristics of the formation indicate that the succession was deposited on a gently sloping epeiric platform on the northern margin of Gondwana. The...

Diverse helcionelloid molluscs, probable polychaetes, and sclerites of other metazoan groups are described from the Brèche à Micmacca Member at section Le IX in the Lemdad syncline in the High Atlas, southern Morocco. The collections include more than 3,000 specimens and complement earlier described faunal assemblages from this interval. The new ma...

Diverse helcionelloid molluscs, probable polychaetes, and sclerites of other metazoan groups are described from the Br` eche a` Micmacca Member at section Le IX in the Lemdad syncline in the High Atlas, southern Morocco. The collections include more than 3,000 specimens and complement earlier described faunal assemblages from this interval. The new...

Earth's "oldest known" cephalopods from the Early Cambrian of SE Newfoundland are not cephalopods. They are best interpreted as post-mortem chimaers consisting of the open apertural chambers of several orthothecid hyoliths with invaginated narrow tubes of Coleoloides. The small tubes are misinterpreted as cephalopod siphuncles. The oldest known cep...

Since 1990, it has been proposed that olenelloid and paradoxidid trilobites overlapped in age, even though the former represents the traditional lower Cambrian of Laurentia and the latter represents the traditional middle Cambrian of the ‘Acadobaltic Realm’ (i.e., Baltica, West Gondwana) and Siberia. Subsequent studies on biostratigraphical correla...

The taxonomically difficult ellipsocephalid trilobites from upper lower Cambrian (unnamed Stage 4) strata in Scandinavia are reviewed and revised. The suggested generic identities illustrate the diversification of the Ellipsocephalinae and advocate a modified correlation of the late to latest early Cambrian strata in Scandinavia and Baltica. The st...

The Avalonia microcontinent has diagnostic terminal Ediacaran–Ordovician lithostratigraphy, depositional sequence architecture, and igneous activity that extends for 2000+ km reflecting epeirogeny related to the Avalonian transform fault. Avalonia records an abrupt early Middle Cambrian (late Wuliuan) change from green, purple, or light grey to ove...

The occurrence of a likely graptolite in lowest Wuliuan strata of the Franconian Forest almost certainly records the oldest known graptolithoid hemichordate in West Gondwana and possibly the oldest graptolite presently known. The fossil is a delicate, erect, apparently unbranched rhabdosome with narrow thecae tentatively assigned to the poorly know...

The occurrence of a likely graptolite in lowest Wuliuan strata of the Franconian Forest almost certainly records the oldest known graptolithoid hemichordate in West Gondwana and possibly the oldest graptolite presently known. The fossil is a delicate, erect, apparently unbranched rhabdosome with narrow thecae tentatively assigned to the poorly know...

Tiout is considered as one of the most visited sections in the world since 1923 and it is also one of the best studied and the most referenced site both regionally and across the western Gondwana (Geyer et al, 1995). It is about 80Km away from Agadir and 20km from Taroudant. It presents a full carbonate platform sequence and outcrop of Cambrian lan...

5 6 Variation in global oxygenation has been regarded as a factor in life's evolution 1. He et al. 2 7 similarly relate metazoan evolution late in the Cambrian Evolutionary Radiation (CER, ca. 525-8 506 Ma) to "extreme oxygen perturbations." This synthesis: 1) Features non-credible fossil 9 diversities (125-300 species/sample) claimed to show CER d...

Extant marine arthropods are afflicted by a variety of parasitic diseases making it plausible that extinct trilobites also had a variety of parasites. Direct evidence in the form of preserved parasite body fossils is lacking to date, which is not surprising considering the poor preservation potential of soft tissues of parasites and their hosts. So...

Eccaparadoxides is a geographically widely distributed trilobite genus that occurs in the middle part of the Cambrian System. However, the systematically important morphologic characteristics that can be used to differentiate taxa are often problematical in their application. A review of the large number (over 30) of significant species or forms as...

The sedimentological and ichnological data of the Mila Group in the Alborz Basin, northern Iran indicate that the appearance of exotic facies and resurgence of microbialites resulted from the development of extraordinary palaeoceanographic conditions with widespread environmental stress and enhanced precipitation of CaCO 3 . Inhospitable environmen...

No basis for controversy exists in the naming of a global, strongly negative, uppermost Cambrian carbon isotope (δ 13 C) excursion. The HERB Event (HERB) has met the standards for chemostratigraphic units (i.e. consistent biostratigraphic brackets, content and concept) since 1992. By comparison, the TOCE excursion morphed through four temporally di...

Distinctive uppermost Ediacaran–Ordovician rocks (Avalonian overstep sequence) were key in definition of Avalonia, which comprises large areas of the NE Appalachians and the Caledonian and Variscan mountains (Britain and western Europe). This siliciclastic-dominated cover succession unconformably overlies a Neoproterozoic pre-Avalonian basement col...

Abstract Tiny snail-like conchs of Pelagiella Matthew are important in discussions of lophotrochozoan and mollusc origins in the Cambrian Evolutionary Radiation (CER). Limited morphologic features of Pelagiella conchs have led to the Pelagiella-problem: 1) poorly distinguished Pelagiella species, 2) an exceptional genus range across all Cambrian p...

Der Muschelkalk im nördlichen Franken und am südlichen Rand Thüringens gehört zum Ablagerungsraum um das Depozentrum des südlichen Teilbeckens im Germanischen Becken. Unter gemäßigter Mächtigkeitsabnahme verzahnen sich die Gesteine nach Osten und Südosten unter zunehmendem Eintrag von Siliziklastika und bei zunehmendem Anteil an dolomitischen Geste...

The stratigraphic architecture, changes of depositional systems in lateral and vertical extent, and 3D-stacking pattern of second- and third-order sequences of the Cambrian successions on the northern Gondwanan margin indicates a distinct sea-level fall in the Alborz Zone and Central Iran corresponding with global sea-level fluctuations. The peak o...

The most famous section in the Cambrian of Morocco is located at Tiout in the Anti-Atlas Range. The section has the oldest trilobites and archaeocyaths in west Gondwana and has yielded precise U-Pb zircon dates through the Early Cambrian (Landing et al., 2020).

Episodic low oxygenated conditions on the sea-floor are likely responsible for exceptional preservation of animal remains in the upper Amouslek Formation (lower Cambrian, Stage 3) on the northern slope of the western Anti-Atlas, Morocco. This stratigraphic interval has yielded trilobite, brachiopod, and hyolith fossils with preserved soft parts, in...

Die Oberer-Muschelkalk-Subgruppe, kurz Oberer Muschelkalk, wird nach Lithologie, Abgrenzung zum Liegenden und Hangenden, Mächtigkeit, geographischer Verbreitung, Biostratigraphie, Leitflächen, Alter und Paläoökologie beschrieben. Aufgeführt werden auch Synonyme, Typgebiet und wirtschaftliche Verwendung. Die Subgruppe umfasst marine Karbonate, Merge...

Die Unterer-Muschelkalk-Subgruppe (vereinfacht: Unterer Muschelkalk) wird nach Lithologie, Abgrenzung zum Liegenden und Hangenden, Mächtigkeit, geographischer Verbreitung, Biostratigraphie, Leitflächen, Alter, Paläoökologie beschrieben. Aufgeführt werden auch Synonyme, Typgebiet und wirtschaftliche Verwendung. Die Subgruppe umfasst marine Karbonate...

Terminal Ediacaran-late early Cambrian deposition, faunas and passive margin evolution of the north Indian margin are recorded in the Nigali Dhar syncline succession. Restudy of the upper Tal Group (upper lower Cambrian Koti Dhaman Formation, KDF) ichnofauna from the Khud-Drabil section reduces it to 18 confidently named forms. The lower KDF (Lower...

The use of “lower,” “middle,” and “upper” has persisted for a generation as a convenient and needed way to divide the Cambrian despite agreement that the system is to be divided globally into four series and ten stages. The traditional tripartite division of the system into regional series (Lower, Middle, Upper) reflected local geological and bioti...

A new ichnogenus and ichnospecies, Segmentichnus mohri, is recognized in the lower Carboniferous deep-sea Culm facies deposits in the southern Germany. The trace fossil is an unusually large, horizontal, tubular burrow with primary successive branching and transverse annulation with ring-like, slightly irregular swellings, without wall, preserved i...

Abstract – The best exposed terminal Ediacaran(?)‒upper lower Cambrian succession on West Gondwana is at Tiout, southern Morocco. The section is crucial in global bio- and chronostratigraphy of the upper lower Cambrian as it has the oldest identifiable West Gondwanan trilobites and archaeocyaths. Its fallotaspids represent one of Earth’s oldest bio...

Chemostratigraphic units require consistent definitions and unambiguous names. So-called TOCE (Top of Cambrian Excursion) is used as an uppermost Cambrian δ ¹³ C carb negative excursion although it was proposed without documentation, is ambiguously defined, and variably correlated into four Laurentian trilobite zones. TOCE, a nihilartikel, is regul...

New U–Pb radioisotopic ages on early Cambrian volcanic zircons condition a high-resolution Bayesian age model that constrains the first occurrences and zonations of West Gondwanan archaeocyaths and trilobites in southern Morocco. The oldest archaeocyaths in the Tiout Member of the Igoudine Formation (519.71 + 0.26/− 0.35 Ma) are c. 6 Ma younger tha...

Trilobites appeared and diversified rapidly in the Cambrian, but it is debated as to whether their radiations and extinctions were globally synchronous or geographically restricted and diachronous. The end of the early Cambrian is a classic example—it has traditionally been defined by the extinction of olenellid and redlichiid trilobites and the ap...

In an article by Geyer and Peel (2017, p. 288), we inadvertently coined a species-group name, Elrathia groenlandica Geyer and Peel, 2017 for a trilobite species of the superfamily Ptychopariacea. This name is a junior homonym of Elrathia ? groenlandica Poulsen, 1927 and is thus invalid (ICZN Article 57.2; see International Commission on Zoological...

The Tamlelt massif is physiographically grouped as a continuation of the easternmost High Atlas. However, re-examination of the Tamlelt's Cambrian litho- and biostratigraphy shows a depositional history that differs from that of the Souss Basin to the southwest (i.e., west-central High Atlas and eastern Anti-Atlas of Morocco). Our re-examination le...

A characteristic group of redlichioid trilobites distributed in the late part of Cambrian Stage 3 and the early part of Cambrian Stage 4 in West Gondwana is revised and interpreted to constitute a monophyletic family Despujolsiidae. More than 25 species were previously assigned to the genera Perrector, Resserops, Eops, Marsaisia, Despojulsia, Pareo...

The new ellipsocephaloid trilobite species Kingaspidoides spinirecurvatus has a spectacular morphology because of a unique set of two long and anteriorly recurved spines on the occipital ring and the axial ring of thoracic segment 8. Together with the long genal spines this whimsical dorsally directed spine arrangement is thought to act as a non-st...

Based on new material, this study summarizes the morphology of Longianda termieri from the lower Cambrian of the Anti-Atlas, Morocco, particularly in respect to its thoracic and pygidial characters. It also discusses the morphology of the genera Saukianda and Pseudosaukianda and the differences between these genera and Longianda. It also summarizes...

Reports on the Avalonia terrane in the Acadian-Caledonian (A-C) mountain belt often feature 1) an homage to a complex late Proterozoic basement and siliciclastic-dominated terminal Edicaran-Ordovician platform cover sequence (E-O cs) with distinctive macrobiotas; 2) sophisticated zircon/stable isotope work as a prelude to geologic history conclusio...

The dominant models for ancient and future global temperatures draw on Svante Arrhenius' 1896 insights. He concluded CO2 was a key temperature driver and anticipated the modern climate catastrophe by calculating the effect of rising industrial CO2 emissions. The link from the late-19 th century of rising temperature with ever higher pCO2 based on a...

Miaolingian rocks of the Delitzsch–Torgau–Doberlug Syncline yield Helcionelloida and Hyolitha that are otherwise poorly known from this stratigraphical interval in Central Europe. The two faunal intervals from the lower part of the Wuliuan and the lower part of the Drumian Stage include the helcionelloid genera Helcionella, Marocella and Leptostega...

The previously poorly investigated trilobite fauna of the upper Igoudine and lowest Amouslek formations in the western Anti-Atlas, Morocco, critical for the understanding of earliest trilobites on a global scale, is studied in detail and its taxonomic diversity and biostratigraphic characteristics reviewed. The key section at Tiout, particularly th...

The previously poorly investigated trilobite fauna of the upper Igoudine and lowest Amouslek formations in the western Anti‐Atlas, Morocco, critical for the understanding of the earliest trilobites on a global scale, is studied in detail and its taxonomic diversity and biostratigraphical characteristics reviewed. The key section at Tiout, particula...

Bradoriid arthropods (class Bradoriida) are described for the first time from the lower–middle Cambrian boundary interval (regional Agdzian Stage) of the Franconian Forest in eastern Bavaria, Germany. The specimens originate from the Tannenknock and Triebenreuth formations, which are part of a shallow marine succession deposited at the margin of We...

Newly identified hyoliths from early Cambrian ‘Small Shelly Fossil’ assemblages in New York State and Quebec extend the geographical ranges of hyolith taxa, otherwise known only from Baltica and Siberia, into eastern Laurentian North America, and in some cases, are accompanied by significant stratigraphical range extensions. The newly recognized ta...

Álvaro et al. (2018) argued that at least six species of Acadoparadoxides described from the lower–middle Cambrian boundary interval successions in the Anti-Atlas of Morocco all belong to Acadoparadoxides mureroensis (Sdzuy, 1958), which was first described from the Iberian Chains, Spain. Their study is based entirely on a morphometric analysis, wh...

Hearing et al. (1) determine a precise sea-surface temperature from late in the diversification of metazoans. However, we contend their global climate synthesis reflects an unquestioning application of the "greenhouse paradigm," a problematical paleogeographic reconstruction, and an extremely high pCO2 incompatible with marine carbonate deposition...

The early middle Cambrian Tannenknock Formation of the Franconian Forest, traditionally subdivided into the Galgenberg and Wildenstein strata, yields a relatively diverse fauna. This fauna includes a number of molluscs, which portrays a fairly diverse assemblage that can be regarded as paradigmatic for the lower–middle Cambrian boundary interval in...

66 trilobites in Germany (Elicki, 1994), by archaeocyaths in South Australia. Thus, recent idea of older (Late Tommotian-Early Atdabanian) age of the South Australian strata, containing these molluscs (Betts et al., 2016, 2017), is absolutely unreasonable. Such a wide geographic distribution of many mollusk species during the Botoman time can be ex...

The lower Cambrian Lalun Formation of the Tabas Block, Central Iran, allows to generate a sequence stratigraphic model which characterises the sedimentary evolution and improves palaeoenvironmental interpretation of sedimentary successions along the northern margin of the Prototethys. This formation provides a key for understanding processes that t...

journal homepage: www.elsevier.com/locate/earscirev Corrigendum Corrigendum to "Early evolution of colonial animals (Ediacaran evolutionary radiation-Cambrian evolutionary radiation-great Ordovician biodiversification interval)" [Earth Sci. Rev. 178 (2018) 105-135]

Re-evaluation of eumetazoan modular coloniality gives a new perspective to Ediacaran–Ordovician animal diversification. Highly integrated eumetazoan colonies (porpitids [“chondrophorines”], pennatulacean octocorals, anthozoans) prove to be unknown in the Ediacaran. Ediacaran Evolutionary Radiation (EER, new term) fossils include macroscopic and mul...

The comments to the Stratigraphic Table of Germany (ESTD 2005) included most complicated and controversial chapters on the Proterozoic to Silurian periods, largely due to the inclusion of disputed allochthonous tectonostratigraphic units. Meanwhile, several of the Proterozoic to/and Early Palaeozoic former stratigraphic units of the Variscides have...

The genus Aladraco nom. nov. is described and discussed, along with two species recognized from coeval strata of the lower traditional middle Cambrian, A. schloppensis (Wurm, 1925) from the Tannenknock Formation of the Franconian Forest region, Germany, and A. ougnatensis sp. nov. from the Jbel Wawrmast Formation of the eastern Anti-Atlas, Morocco....

The Coburg Sandstone member of the Hassberge Formation, Middle Keuper, Carnian, Upper Triassic, in the Germanic Basin of Central Europe contains spinicaudatan branchiopods which considerably broaden the known spectrum and provide important data on the phylogenetic history and intercontinental correlation of this systematic group. The spinicaudatan...