Jens Lehmann

Jens Lehmann
Universität Bremen | Uni Bremen · Department of Geosciences

Professor

About

153
Publications
54,792
Reads
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1,601
Citations
Citations since 2017
25 Research Items
701 Citations
2017201820192020202120222023020406080100120140
2017201820192020202120222023020406080100120140
2017201820192020202120222023020406080100120140
2017201820192020202120222023020406080100120140
Introduction
Jens Lehmann works at the Department of Geosciences, Universität Bremen. Jens does research in Paleontology, Paleoclimatology and Geology. His current projects are 'The Anisian (Middle Triassic) Ammonoids of Nevada - An Integrated Approach to Understand Morphological Change' and 'The Ammonoidea of the Lower Greensand - A revision'.
Additional affiliations
February 2019 - present
Universität Bremen
Position
  • Professor
October 2000 - present
Universität Bremen
Position
  • Head of Department
March 1999 - September 2000
University of Tuebingen
Position
  • PostDoc Position

Publications

Publications (153)
Article
Changes in ammonite morphology during the earliest Early Aptian (Cretaceous) of an epicontinental sea in northern Germany were investigated based on new and rich material of Deshayesites (Deshayesitidae). This is a globally distributed genus and one of the most important ammonites of the Cretaceous with respect to biostratigraphy and abundance. The...
Chapter
Ammonites are often dominant elements of Early Cretaceous marine faunas. Many species are important index fossils, in some cases with worldwide distribution. We review the paleobiogeography for the Early Cretaceous. We recognize three major faunal phases in the distribution of ammonites during that interval. The first phase, directly inherited from...
Article
Full-text available
A reassessment of Glaphyrites material from the Late Carboniferous of Uruguay, famous for being the first ammonite described with the complete buccal mass in situ (also referred to Eoasianites earlier), indicates that the structures recorded as opercula or anaptychi, respectively, by earlier authors in several of the Glaphyrites specimens are rathe...
Article
Oceanic Anoxic Events (OAEs) of the Mesozoic are manifested globally by deposition of laminated, organic-rich sediments at depths ranging from the deep ocean to the shallow, epicontinental seas. In the deep ocean, the deposition of the OAE black shales is known to have been associated with the development of anoxic or dysoxic conditions. However, l...
Article
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Careful preparation released an ammonite specimen from a block of highly indurated sandy limestone from the oyster bed of the Wanderfeld IV occurrence in Namibia. This find is important because Wanderfeld IV is one of two known marine onshore Cretaceous deposits on the west coast of Africa south of Angola. Although ammonites often permit precise da...
Article
Full-text available
Beyrichitine ammonoids of NV Nevada reveal a high taxonomic diversity of Anisian (Middle Triassic). This diversity is, however, in contrast to their relatively low morphologic disparity. Depending on the exact definition, morphologic disparity of a data set is a direct consequence of the sum of all ontogenetic changes. In the past, however, the int...
Article
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We document an upper upper Albian (Mortoniceras rostratum Zone) cephalopod assemblage from Clansayes (Drôme, south-eastern France). Although fossils are rare in local exposures and in the single sampled level, a decade of intensive fossil collecting yielded 290 ammonite and 5 nautilid specimens. In total, we describe 1 spe- cies of nautilid and 24...
Article
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Peat bogs as anthropogenic wildlife traps? – Bone assemblages of the fallow deer (Dama dama) in the Vehmsmoor (Lower Saxony). – The Vehmsmoor to the west of Walsrode in Lower Saxony is a degenerated raised bog and as peat cutting by farmers in this area has never been renaturalised, in some places the resulting pits are now filled with soft bog soi...
Article
Tropaeum is a genus of large to very large heteromorph ammonites, typical of the Aptian and among the dominant invertebrate organisms of its time. Here we describe a new species, Tropaeum (Tropaeum) evolutum sp. nov., from the basal upper Aptian Epicheloniceras martinioides Zone of the now back-filled Coombe Quarry at Maidstone, Kent, southern Engl...
Article
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The occurrence of the nautiloid genus Anglonautilus Spath in France was limited to the report of Anglonautilus dorsoplicatus (Wiedmann) from the Albian of Escragnolles (Alpes-Maritimes) and Anglonautilus sp. from the Aptian of Les Ferres (Alpes-Maritimes). Here we document the presence of the successive species Anglonautilus praeundulatus Lehmann e...
Article
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Obituary for Werner Beckert (1938-2021), who collected many thousand fossils from early Cretaceous boulders from the glacial drift during his lifetime and co-authored a couple of papers on this topic.
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Ammonoids reached their greatest diversity during the Triassic period. In the early Middle Triassic (Anisian) stage, ammonoid diversity was dominated by representatives of the family Ceratitidae. High taxonomic diversity can, however, be decoupled from their morphologic disparity. Due to its high phenotypic variability, the high diversity of cerati...
Article
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The Salazac locality (Gard, southeastern France) is renowned for the richness of its cephalopod fauna (especially ammonites) from the Mortoniceras fallax Zone (uppermost Albian, Lower Cretaceous). However, most ammonite species have paradoxically been scarcely illustrated up to now. Furthermore, the rare assessments of ammonite taxonomic diversity...
Article
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A new pycnodont taxon, Njoerdichthys dyckerhoffi gen. et sp. nov., from the Turonian of the Lower Saxony Basin of Germany is described and its systematic positions is established based on phylogenetic analyses of three specimens using slightly altered data matrices. All analyses display some differences to previous analyses but show very similar re...
Article
Dufrenoyia is a relevant ammonite genus for discussing the lower–upper Aptian boundary on a supraregional scale. We present the first comprehensive account on the genus from Germany, recording the two index species Dufrenoyia furcata and D. transitoria from the Ahaus area. This is based on a yet undescribed historical collection by the German ninet...
Article
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Ptychites is among the most widely distributed ammonoid genera of the Triassic and is namesake of a family and superfamily. However, representatives of the genus mostly show low-level phenotypic disparity. Furthermore, a large number of taxa are based on only a few poorly preserved specimens, creating challenges to determine ptychitid taxonomy. Con...
Article
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The identifications of some ammonite findings from the Aptian–Albian boundary interval of the type locality of the Serdj Formation at Djebel Serdj in north-central Tunisia are revised and their biostratigraphic value is discussed. From this stratigraphic section a single belemnite finding is described that has been previously identified as Neohibol...
Article
The Lower Greensand Group on the Isle of Wight in southern England forms the basis for the Aptian ammonite biostratigraphy in western Europe mainly established by the work of Raymond Casey between 1960 and 1980. It thus became a world reference succession, due to many ammonite finds from excellent outcrops along the coastline of the Island exposing...
Article
Reconstructing marine paleoenvironments from the skeletal hardparts of nektic organisms is often hampered by their unknown migrational pathways involving different water masses and their corresponding physico-chemical parameters. Despite significant progress over the last years, the reconstruction of migration patterns of extinct ammonoids is diffi...
Chapter
The Geosciences Collection of the University of Bremen is a mid-size collection of estimated about 800,000 specimens that are housed at the Faculty of Geosciences of the University of Bremen. It is focused on the field of research in paleontology. The collections include more than 500,000 individual fossils, most of these are ammonoids, a focus tha...
Article
Aptian and Albian parahoplitid ammonites from the Sanganeh- and Aitamir formations of the Koppeh Dagh Basin in northern Iran are described and illustrated, some taxa are recorded from Iran for the first time. The earlier established view of a close palaeobiogeographic affinities of the Koppeh Dagh Basin with the European faunal realm during the lat...
Preprint
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Book chapter of Beck & Joger (eds.) about the Palaeontological Collections in Germany, Austria and Switzerland
Chapter
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Im Kapitel "Ammoniten (Ammonoidea)" des Buches "Fossilien im Alpstein - Kreide und Eozän der Nordostschweiz" (Kürsteiner Peter und Klug Christian 2018) wird eingegangen auf: Anatomie, Ursprung und Evolution, Dimorphismus, Lebensweise, Aussterben, Klassifikation. Im Hauptteil des Kapitels werden die verschiedenen Ammoniten-Arten - rund 80 Taxa - auf...
Article
Microfossil analyses of samples of upper Turonian to Coniacian (Upper Cretaceous) sedimentary rocks from Tanzania Drilling Project site 31 have documented ammonoid nuclei (earliest whorls). In spite of the limited number of morphological characters, some Lytoceratina (including the heteromorph Turrilitoidea) could be identified at the family level...
Article
The cymatoceratid nautilid genus Anglonautilus is distinguished from most other post-Triassic nautiloids by the occurrence of pronounced fold-like undulating ribs on the phragmocone and early body chamber. Anglonautilus praeundulatus n. sp. is described from the lower Aptian of eastern Spain. It is the first record of this genus from Spain and cons...
Article
Full-text available
Locally, the sandur deposits of Wolgast-Hohendorf, Mecklenburg-Vorpommern, NE-Germany, contain abundant erratic boulders of the late Early Cretaceous (early Albian). Occasionally, these boulders yield ammonites of the Leymeriella tardefurcata Zone and possibly earliest Douvilleiceras mammillatum Superzone. A first comprehensive account of the syste...
Article
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Whitening of fossils for scientific photography is a well-established method in palaeontology for more than 100 years. A number of different techniques have been invented, the authors describe these general methods and compare the results with respect to quality and practicability. The following techniques are embraced: Coating with color chalk, ai...
Article
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Background Fossil ticks are extremely rare and Ixodes succineus Weidner, 1964 from Eocene (ca. 44–49 Ma) Baltic amber is one of the oldest examples of a living hard tick genus (Ixodida: Ixodidae). Previous work suggested it was most closely related to the modern and widespread European sheep tick Ixodes ricinus (Linneaus, 1758). Results Restudy us...
Article
The Alpstein (cantons of Appenzell Ausserrhoden, Appenzell Innerrhoden and St. Gallen, northeastern Switzerland) has been of great interest for geologists over the last decades because of its excellent outcrops. However, there was no comprehensive overview over its Cretaceous fossil content. Here, we describe the cephalopod associations, which are...
Article
Changes in ostracod assemblage composition from the Lower Aptian of the Lower Saxony Basin (Germany) are investigated to estimate their potential as proxies for palaeoenvironmental habitat changes in an epicontinental setting. The studied palaeoenvironmental factors include oxygen depletion, increasing temperatures during OAE 1a and an increasing w...
Chapter
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Typically planktonic foraminiferans of the Cretaceous characterize open water environments covering the outer shelf to pelagic realm. In fact, this group was apparently completely avoiding nearshore, shallow environments. Here we report planktonic foraminiferans in a succession covering the major transgression around the Early/Late Aptian boundary...
Research
Full-text available
Diploma thesis, 1995: Stratigraphy and facies of the Alba Formation (Carboniferous) near Santa Olaja de la Varga, with a short account on the late Palaeozoic of the southern Aguasalia syncline, N-Spain
Chapter
Full-text available
Ammonoidea were dominant elements of marine Cretaceous faunas. Their fossils are important biostratigraphic indicators, in some cases with worldwide distribution. Their paleobiogeographic distributions were influenced by changing continental positions, currents, sea level change, and perhaps by their mode of life as reflected in the evolution of ma...
Chapter
Full-text available
An ammonite zonation of the Cretaceous period is presented, which largely follows the Geological Time Scale 2012, with illustrations of several index species. Concepts of Cretaceous ammonite biostratigraphy are briefly discussed and characteristic examples of the types of zones and ammonite events are given. Furthermore, accomplishments and limits...
Chapter
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Soft-tissue preservation is very rare in ammonoids. The reconstruction of the internal anatomy relies on few specimens with exceptional preservation, comparisons with recent cephalopods, and inferences based on the extant phylogenetic bracket. Herein, we describe the current knowledge of the soft part-anatomy of ammonoids. Of the digestive tract, t...
Chapter
Ammonoidea were dominant elements of marine Cretaceous faunas. Their fossils are important biostratigraphic indicators, in some cases with worldwide distribution. Their paleobiogeographic distributions were influenced by changing continental positions, currents, sea level change, and perhaps by their mode of life as reflected in the evolution of ma...
Conference Paper
Full-text available
Due to excellent outcrops and a long collecting tradition, the rich Aptian ammonite faunas from southern England are well known and important for comparison with Aptian successions across the world. The Lower Greensand ammonite monograph by Raymond Casey (1960-1980) was published by this Society. It constitutes a very important piece of work on a s...
Article
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The Lower Cenomanian part of the Mzinene Formation of northern KwaZulu-Natal has yielded a diverse assemblage of representatives of the cosmopolitan ammonite subfamily Mantelliceratinae Hyatt, 1903. The following species are recognized: Mantelliceras mantelli (J. Sowerby, 1814), M. cantianum Spath, 1926a, M. picteti Hyatt, 1903, M. couloni (d’Orbig...
Chapter
Full-text available
Article
Late Albian ammonite faunas from the Aitamir Formation of the Koppeh Dagh Basin in northeast Iran are described and illustrated. These comprise 14 taxa, several of which are recorded from Iran for the first time, namely Anahoplites planus (formerly recorded from central Iran in open nomenclature only), Semenoviceras solidus, Epihoplites (Metaclavit...
Article
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Systematics of the turtles (Anapsida: Chelonii) of Upper Jurassic and Early Cretaceous from northwest Germany: The present studys aim is to bridge the gap in the investigation of Upper Jurassic and Lower Cretaceous fossil turtles from northwest Germany, present since the latest publication of OERTEL (1924). The presently known and accessible materi...
Article
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Early Cretaceous glauconitic sandstones form part of the well-established boulder association known in the German literature on glacial erratics as the “Ahrensburger Geschiebesippe”. Because ammonites are very rare in these sandstones, a small assemblage is described, based on material mentioned in several classical papers. The following taxa are r...
Article
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A new Early Albian ammonite fauna is described from erratic boulders of morainal plain deposits at Wolgast-Hohendorf near Greifswald in north-eastern Germany. They contain species indicative essentially of the Proleymeriella schrammeni Zone, the Leymeriella tardefurcata Zone and possibly the earliest Douvilleiceras mammillatum Superzone. This dates...
Article
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Discovery of a single specimen of brachyurous decapod crustacean in late Albian gray claystone extracted from the Hannover-Lahe core, Germany, permits description of a new species of Etyidae Etyus makrochele. The discovery extends the geographic range of the genus into the Lower Saxony Basin in north-west Germany.
Article
A middle latitude (c. 40° N) flora from the Lower Cretaceous of Coppengrave close to Duingen, north-western Germany, has been investigated. The newly collected fossils are preserved as impressions and compressions, some yielding cuticular details. Twenty-one species have been identified. The flora is dominated by ginkgophytes and conifers, whilst o...
Article
Full-text available
A fairly complete lower jawof an adult mammoth from the stream bed of the RiverWeser in Bremen-Vegesack contains both molars (M3).The number of enamel lamellae of the molars is each 23, probably the specimen deceased at an individual age of more than 50 years. The bone is well-preserved and contains around 10 percent collagen in comparison with fre...
Article
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From thinly laminated marlstones of the Hesseltal Formation, representing the Late Cenomanian Oceanic Anoxic Event (OAE) 2, at Lengerich in the Teutoburger Wald (Westfalen, north-west Germany), 17 sediment-compacted baculitid ammonites with carbonised and partially phosphatised soft parts are recorded. Some preserve remains of the buccal mass, incl...
Article
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Lehmann, J., Friedrich, O., von Bargen, D. and Hemker, T. 2012. Early Aptian bay deposits at the southern margin of the lower Saxony Basin: Integrated stratigraphy, palaeoenvironment and OAE 1a. Acta Geologica Polonica , 62 (1), 35-62. Warszawa. The present study establishes a lithostratigraphic subdivision, a bio- and chemostratigraphy and describ...
Chapter
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Article
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For the first time, a large number of belemnite arm hooks is described from the Lower Cretaceous (Middle-Upper Albian boundary interval) of the classic locality of Folkestone in southern England. The arm hooks originate from six individual claystone layers; some could have been attributed to the parataxon Arites sp. Comparison is made with material...
Article
Full-text available
The ammonite biostratigraphy of the Middle/Late Albian boundary interval in northern Germany has been significantly improved in the past few years by the Hannover-Lahe and Hannover-Kirchrode borehole sections. Both sections show are monotonous claystone successions deposited in a deep sub-basin of the Lower Saxony Basin. Here ammonite data of the H...
Article
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Pronounced paleotemperature variations associated with the carbon cycle perturbations of oceanic anoxic events (OAEs 1b and 1d) are known to have occurred during the early and latest Albian. However, reliable paleotemperature data spanning the 12 m.y. between these two events are sparse. Here we present 18O, 13C, and Mg/Ca data for the middle to ea...
Article
Full-text available
Boreal Aptian-Albian marine sediments of the Hannover region (northern Germany) mainly consist of dark to medium grey claystones, which were deposited in the central part of the Lower Saxony Basin. Calcareous dinoflagellate cyst samples of the Vöhrum clay pit, east of Hannover, yield a diverse flora of latest Aptian-earliest Albian (H. jacobi/L. sc...
Article
Full-text available
Two Cenomanian–Turonian boundary (CTBE) sections (KB3 and GM3) of the Karak–Silla intra-platform basin of the Eastern Levant carbonate platform, Jordan, are correlated based on high-resolution calcimetry. KB3 contains black shales with over 7 wt% total organic carbon (TOC). GM3 was deposited at shallower water depth and reveals four conspicuous gyp...
Article
Full-text available
The Upper Barremian-Albian Levant Platform was studied in North Sinai and Israel (Galilee and Golan Heights) by bio- and lithostratigraphy, facies analyses, and sequence stratigraphy. Integrating shallow-marine benthic foraminifera (mainly orbitolines), ammonite, and stable isotope data resulted in a detailed stratigraphic chart. Transects across t...
Conference Paper
Lower Cretaceous deposits of the Hannover region, northern Germany, mainly consist of dark to medium grey claystones, which originate from marine sedimentation in the central area of the so-called Lower Saxony Basin. The investigation of calcareous dinoflagellate cyst assemblages from 14 claystone samples of the Vöhrum clay pit, east of Hannover, y...
Article
Full-text available
During the Aptian, some carbonate platforms of the sub-tropical realm (for example, on the northern Tethys margin or in the Gulf of Mexico) were affected repeatedly by severe perturbations in the carbonate production factory and drowning, preferentially during global warming events such as the Early Aptian Oceanic Anoxic Event 1a and a prominent mi...
Thesis
Preface (modified): The Cretaceous lasted 80 million years, constituting this period as the longest period during the history of life on Earth. There are quite a lot of superlatives about the Cretaceous, like extreme climates, enormous superplumes, strong sea level changes with possibly the peak sea level of the whole Phanerozoic, and a strong incr...
Article
Full-text available
New stable carbon and oxygen isotope data from an Upper Cretaceous section in Tibet are presented, and compared to carbon isotope records from England, Italy, and Germany. Together with a stratigraphic re-interpretation of published carbon isotope data from a nearby section in Tibet, our data can surprisingly well be correlated with the European se...