Research projects

Current plesiosaur research projects

Revision of the plesiosaur diversity of the Posidonia Shale

Contributors: Daniel Madzia, Miguel Marx, Benjamin Kear, Pascal Abel, Aubrey Roberts, Oliver Hampe and others

Published so far:

• Sachs, S., Madzia, D., Marx, M., Roberts, A., Hampe, O. & Kear, B.P. (2025) The osteology, taxonomy, and phylogenetic placement of Seeleyosaurus guilelmiimperatoris (Plesiosauroidea, Microcleididae) from the Lower Jurassic Posidonia Shale of Germany. The Anatomical Record: 1-62. 

• Sachs, S., Abel, P. & Madzia, D. (2023) Unusual plesiosaur vertebrae from the Lower Jurassic Posidonia Shale of Germany. Historical Biology 36(10):  2124-2132.

• Marx, M., Sjövall, P., Jarenmark, M., Eriksson, M.E., Kear, B., Sachs, S., Nilkens, K., Op De Beeck, M. & Lindgren, J. (2023) Preserved skin with putative scales in a new plesiosaur from the Jurassic Posidonia Shale of Germany. 8th International Meeting on Mesozoic fishes and aquatic tetrapods Abstract Volume: 39.

Revision of the Microcleididae

Contributors: Daniel Madzia, Miguel Marx, Ben Thuy

Published so far:

• Sachs, S., Madzia, D., Marx, M., Roberts, A., Hampe, O. & Kear, B.P. (2025) The osteology, taxonomy, and phylogenetic placement of Seeleyosaurus guilelmiimperatoris (Plesiosauroidea, Microcleididae) from the Lower Jurassic Posidonia Shale of Germany. The Anatomical Record: 1-62. 

Plesiosaurs from the Lower to Middle Jurassic transition

Contributors: Daniel Madzia, Stefan Eggmaier

Published so far:

• Sachs, S., Eggmaier, S. & Madzia, D. (2024) Exquisite skeletons of a new transitional plesiosaur fill gap in the evolutionary history of plesiosauroids. Frontiers Earth Sciences 12: 1-10.

• Sachs, S., Eggmaier, S. & Madzia, D. (2023) A new ‘transitional’ plesiosaur from the uppermost Lower Jurassic of Germany. – In: Alba, D.M., Marigó, J., Nacarino-Meneses, C., Villa, A. (Eds.) Book of Abstracts of the 20th Annual Conference of the European Association of Vertebrate Palaeontologists. Palaeovertebrata, Special Volume 1: 232.

Brachauchenine pliosaurids - taxonomy and diversity

Contributors: Daniel Madzia and others

Published so far:

• Bastiaans, D., Madzia, D., Carillo-Briceno, J.D. & Sachs, S. (2021) Equatorial pliosaurid from Venezuela marks the youngest South American occurrence of the clade. Scientific Reports 11, 15501.

• Madzia, D., Sachs, S. & Lindgren, J. (2019) Morphological and phylogenetic aspects of the dentition of Megacephalosaurus eulerti, a pliosaurid from the Turonian of Kansas, USA, with remarks on the cranial anatomy of the taxon. Geological Magazine 156(7): 1201-1216.

• Madzia, D., Sachs, S. & Lindgren, J. (2017) The dentition of Megacephalosaurus eulerti (Plesiosauria, Pliosauridae) from the Turonian of Kansas and comments on the phylogenetic relationships of the last brachauchenines. The Palaeontological Association, Abstracts of Annual Meeting, London: 93.

• Madzia, D., Sachs, S., Evans, M., Lindgren, J., Kear, B.P. & Cau, A. (2017) Reappraisal of the ʽDorking Specimen’: An Upper Cretaceous brachauchenine pliosaurid from England. 15th Annual Meeting of the European Association of Vertebrate Palaeontologists Munich, Germany. Zitteliana 91: 55-56.

Previous plesiosaur research projects

Plesiosaur diversity in the Lower Cretaceous of Germany

Contributors: Jahn J. Hornung, Benjamin P. Kear, Jens Lallensack and others

Publications:

• Sachs, S., Hornung, J.J., Lallensack, J. & Kear, B.P. (2018) First evidence of a large predatory plesiosaurian from the Lower Cretaceous non-marine ‘Wealden facies’ deposits of northwestern Germany. Alcheringa: An Australasian Journal of Palaeontology 42(4): 501-508. 

• Sachs, S., Hornung, J. J. & Kear, B. P. (2017) A new basal elasmosaurid (Sauropterygia: Plesiosauria) from the Lower Cretaceous of Germany. Journal of Vertebrate Paleontology 37(4): e1301945 [more about this study].

• Sachs, S., Hornung, J.J. & Kear, B.P. (2016) Reappraisal of Europe’s most complete Early Cretaceous plesiosaurian: Brancasaurus brancai Wegner, 1914 from the “Wealden facies” of Germany. PeerJ 4 (5745).

• Sachs, S., Hornung, J.J., Lallensack, J. & Kear, B.P. (2016) Evidence for a Simolestes-like plesiosaurian from the Berriasian (Lower Cretaceous) limnic-brackish Bückeberg group of northwestern Germany. In: Sachs, S., Kear, B.P. & Lindgren (eds) 5th Triennial Mosasaur Meeting – a global perspective on Mesozoic marine amniotes. Abstracts and Program: 35-37.

• Sachs, S., Hornung, J., Wohlsein, P. & Kear, B. (2015) A new basal elasmosaurid skeleton with joint pathologies from the Lower Cretaceous of Germany. In: J. Jagt, G. Hebda, S. Mitrus, E. Jagt-Yazykova, A. Bodzioch et al. (eds.) EAVP. XIII Meeting Opole, Abstracts: 131.

• Hornung, J.J., Sachs, S. & Kear, B.P. (2013) Sauropterygian fossils from the predominantly limnic–brackish Bückeberg Formation (Berriasian–Early Valanginian, Early Cretaceous) of northwestern Germany – diversity, distribution, and palaeoecology. In: Reitner, Yang, Wang & Reich (eds.) Palaeobiology and Geobiology of Fossil Lagerstätten through Earth History: 75.

Late Cretaceous elasmosaurids

Contributors: Benjamin P. Kear, Johan Lindgren, Daniel Madzia and others

Publications:

• Sachs, S., Lindgren, J., Madzia, D. & Kear, B.P. (2021) Cranial osteology of the mid-Cretaceous elasmosaurid Thalassomedon haningtoni from the Western Interior Seaway of North America. Cretaceous Research 123: 104769.

• Sachs, S., Lindgren J. & Kear, B.P. (2018) Reassessment of the Styxosaurus snowii (Williston, 1890) holotype specimen and its implications for elasmosaurid plesiosaurian interrelationships. Alcheringa: An Australasian Journal of Palaeontology 42(4): 560-574 [more about this study].

• Sachs, S. & Ladwig, J. (2017) Reste eines Elasmosauriers aus der Oberkreide von Schleswig-Holstein in der Sammlung des Naturkunde-Museums Bielefeld. Berichte Naturwissenschaftlicher Verein für Bielefeld und Umgegend 55: 28-36.

• Sachs, S. & Kear, B.P. (2017) Redescription of the elasmosaurid plesiosaurian Libonectes atlasense from the Upper Cretaceous of Morocco. Cretaceous Research 74: 205-222 [more about this study]. 

• Sachs, S., Kear, B.P. & Lindgren, J. (2016) Re-description of Thalassomedon haningtoni – an elasmosaurid from the Cenomanian of North America. In: Sachs, S., Kear, B.P. & Lindgren (eds) 5th Triennial Mosasaur Meeting – a global perspective on Mesozoic marine amniotes. Abstracts and Program: 38-40.

• Sachs, S. & Kear, B.P. (2015) Fossil Focus: Elasmosaurs. Palaeontology Online, Volume 5, Article 2: 1-8.

• Sachs, S. & Kear, B.P. (2015) Postcranium of the paradigm elasmosaurid plesiosaurian Libonectes morgani (Welles, 1949). Geological Magazine 152(4): 694-710.

• Sachs, S., Kear, B.P. & Everhart, M. (2013) Revised vertebral count in the ‘‘longest-necked vertebrate’’ Elasmosaurus platyurus Cope 1868, and clarification of the cervical-dorsal transition in Plesiosauria. PLoS ONE 8(8): e70877.

Previous thalattosuchian research projects

Thalattosuchian diversity and taxonomy of Germany (Meereskrokodile Project)

Contributors: Mark T. Young, Pascal Abel, Michela Johnson, Steve Brusatte and others

Publications:

• Sachs, S., Young, M. T., Hornung, J. J., Cowgill, T., Schwab, J. A. & Brusatte, S. L. (2024) A new genus of metriorhynchid crocodylomorph from the Lower Cretaceous of Germany. Journal of Systematic Palaeontology 22(1): 2359946.

• Abel, P., Sachs, S. & Young, M.T. (2021) Das Drügendorfer Krokodil ein fränkischer Riese mit europaweiter Verwandtschaft. Fossilien 2021(5): 24-31.

• Sachs, S., Young, M.T., Abel, P. & Mallison, H. (2021) A new species of Cricosaurus (Thalattosuchia, Metriorhynchidae) based upon a remarkably well-preserved skeleton from the Upper Jurassic of Germany. Palaeontologia Electronica 24(2): a24.

• Sachs, S., Young, M. T. & Hornung, J.J. (2020) The enigma of Enaliosuchus, and a reassessment of the Lower Cretaceous fossil record of Metriorhynchidae. Cretaceous Research 114, 104479. 

• Sachs, S., Young, M. T. & Hornung, J.J. (2020) Reassessment of Enaliosuchus schroederi, a metriorhynchid crocodylomorph from the Lower Cretaceous of northern Germany. 2nd Palaeontological Virtual Congress. Book of abstracts: 141.

• Abel, P., Sachs, S. & Young, M. T. (2020) Metriorhynchid crocodylomorphs from the lower Kimmeridgian of Southern Germany: evidence for a new large-bodied geosaurin lineage in Europe. Alcheringa 44(2): 312-326.

• Sachs, S., Johnson, M.M., Young, M.T. & Abel, P. (2019) The mystery of Mystriosaurus: redescribing the poorly known Early Jurassic teleosauroid thalattosuchians Mystriosaurus laurillardi and Steneosaurus brevior. Acta Palaeontologica Polonica 64(3): 565-579 [more about this study].

• Sachs, S., Young, M., Abel, P. & Mallison, H. (2019) A new species of the metriorhynchid crocodylomorph Cricosaurus from the Upper Jurassic of southern Germany. Acta Palaeontologica Polonica 64(2): 343-356 [more about this study].

• Abel, P., Sachs, S. & Young, M. T. (2018) Thalattosuchian remains from the late Aalenian Eisensandstein Formation of Baden-Württemberg, southwestern Germany. Geobonn 2018, Abstracts: 223.