Samuel L. A. Cooper

• Dr. Rer. Nat. (PhD)
• Post-Doctoral Researcher at State Museum of Natural History Stuttgart

Reduction in lepisosteoid-type scales occurred several times in various neopterygian groups, especially on the teleost stem. This reduction resulted in the repeated evolution of either modified lepisosteoid-type, amioid-type, or cycloid scales, defined by a combination of histological and macroscopic features. Amongst pachycormid fishes, lepisosteo...

Pachycormidae is a group of pelagic Mesozoic teleosteomorph fishes characterized by, among other characters, a reduction of the body scales, both in size and also in degree of mineralization. However, a detailed understanding of the timing and mechanism underlying scale reduction remains elusive, and histological sections of the body scales of a pa...

An articulated and mostly complete skull roof of the enigmatic Early Jurassic chondrosteid fish, † Gyrosteus mirabilis Woodward ex Agassiz is described from the Whitby Mudstone Formation (Toarcian) of Whitby, York-shire. Known since the 1830s, isolated bones attributable to this taxon are frequently found along the Whitby coast, although articulate...

The Middle–Late Triassic Grabfeld Formation formed in a generally arid, hostile setting with frequent evaporation under alternating sabkha and playa conditions. Here we report evidence of four temnospondyl taxa from the upper part of the sequence (‘Bunte Estherienschichten’), including (1) Metoposaurus sp., (2) a capitosaur, (3) Gerrothorax sp. and...

The diets and feeding strategies of pterosaurs remain a poorly known although speculatively debated topic in vertebrate paleontology. Fossilized gut contents, which offer a crucial direct line of evidence to help decipher these elusive questions, are only known from a handful of pterosaur specimens in a few notable fossil Lagerstätten, such as the...

Several fragmentary remains of an enigmatic acipenseriform, the order of fishes that includes living sturgeons and paddlefishes, are described from the Upper Jurassic Kimmeridge Clay Formation of southern England. These remains are significant because they represent the first definitive evidence of an acipenseriform from the Upper Jurassic describe...

A partial caudal fin of a large-bodied asthenocormine pachycormiform (Pachycormiformes: Pachycormidae: Asthenocorminae) is described from the Upper Jurassic (lower Tithonian) Kimmeridge Clay Formation of Dorset, England. The specimen comprises associated fin rays, basal fulcra, ‘epurals’ and paired pre-caudal scutes, the combination and morphology...

Pachycormiformes is a Mesozoic clade of stem-teleost actinopterygian fishes famed for their high morphological and ecological disparity. Seemingly coinciding with their first emergence in the fossil record, pachycormids during the Toarcian are already fairly diverse and display various diets and feeding strategies. The dietary ecology of pachycormi...

e non-neopterygian group †Coccolepididae, a moderately diverse predominantly freshwater family, remains an imperfectly known Mesozoic group of actinopterygians, currently classified within Chondrostei based on the presence of several acipenseriform synapomorphies. Coccolepidids first appear during the Early Jurassic in marine sediments, although th...

Cannibalism (conspecific predation) is a surprisingly common and widespread behavior in modern ecosystems; however, direct evidence for cannibalism is strongly lacking in the fossil record. Identifying cannibalism is important to help better understand recondite trophic interactions between extinct species, as well as to detect potential resource p...

Upper Cretaceous coastal marine deposits are widespread in the Southern Urals with a number of marine vertebrates previously reported from this region. However, previous studies on the vertebrate faunas in this region often lack detailed taxonomic descriptions and illustrations, rendering comparisons to other faunal assemblages difficult. A new di...

A remarkable specimen of the actinopterygian fish Pachycormus macropterus from the Early Jurassic (Toarcian) Posidonienschiefer Formation of Germany exceptionally preserves an unusually large ammonite inside its gut. The ammonite was swallowed by the fish, likely by accident, and represents the first direct evidence for an actinopterygian fish cons...

Abstract for oral presentation, presented to the congress of the 8th International Meeting of Mesozoic Fishes and Secondarily Aquatic Tetrapods, Stuttgart, 2023

Ganoine-scaled fishes belonging to the superfamily Lepisosteoidea, more commonly known as gars, are an ancient lineage with origins in the Mesozoic, first appearing in the Kimmeridgian, Late Jurassic. The Mesozoic gar fossil record is patchy, mostly consisting of disarticulated remains, with only a few partially or mostly complete specimens being e...

Pachycormiformes is a diverse clade of stem-teleost actinopterygian fishes with a stratigraphic range from the Lower Jurassic (Toarcian) to Upper Cretaceous (Maastrichtian). The Toarcian Posidonienschiefer Formation in SW Germany records the earliest occurrence of †Pachycormiformes in the fossil record, offering unique and crucial insight into the...

Abstract: The Early Jurassic Posidonienschiefer Formation in south-west Germany (Toarcian) records the first appear�ance of the stem-teleost group Pachycormidae in the fossil record. However, most pachycormid taxa remain poorly diag�nosed or undescribed, making questions of the morphological underpinnings of trophic diversification in the group dif...

Here we present our preliminary description of a new genus and species of pachycormiform fish (Pachycormiformes) from the Lower Jurassic (Toarcian) Posidonienschiefer Formation at Holzmaden, SW Germany. Phylogenetic analysis identifies the new taxon as holding an intermediate position between Saurostomus and Ohmdenia at the base of the suspension-f...

Large vertebrate carcasses contain significant amounts of nutrients that upon death are transferred from the water column to the benthos, enriching the immediate environment. The organisms exploiting these ephemeral resources vary as the carcass decays, creating an ecological succession: mobile scavengers arrive first, followed by enrichment opport...

Isolated jaw elements (vomers, prearticulars, premaxillae) of pycnodont fishes (Actinopterygii: Pycnodontiformes) occur frequently within the Moroccan Oulad Abdoun phosphate assemblages, although their taphonomy has remained unstudied. Recent collecting has identified two conflicting taphonomies: unetched (unaltered) and etched. Three etched jaw sp...

The Upper Cretaceous (Turonian) Akrabou Formation at Asfla in south east Morocco is a marine carbonate succession well-known for its exceptionally preserved, often three-dimensional marine vertebrate fossils. It is perhaps best known for its diverse ichthyological assemblage comprising both cartilaginous and bony fishes, notably teleosts and pycnod...

An isolated, articulated, but crushed ossified lung of a mawsoniid ceolacanth is reported from uppermost Cretaceous (upper Maastrichtian) of Oued Zem, Morocco. The specimen is the last record of a coelacanth before their pseudo-extinction at the end of the Mesozoic. The secimen is also the first record of a marine coelacanth in the Mesozoic of Moro...

The Upper Cretaceous (upper Cenomanian–middle Turonian) Akrabou Formation of Asfla, southeast Morocco is renowned for exceptionally preserved, often three-dimensional bony and cartilaginous fish fossils. Teleosts, rare holosteans and chondrichthyans are well known from the so-called ‘Goulmima ichthyological assemblage’, however pycnodonts (Actinopt...