Neil H. Landman's research while affiliated with American Museum of Natural History and other places
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Publications (321)
Understanding the mechanism of selective extinction is of utmost importance to predict the impact of current anthropogenic environmental changes on the ecosystem. The Cretaceous-Paleogene (K-Pg) mass extinction event has attracted the attention of both the general public and researchers due to its selective nature. In the marine realm, ammonoids an...
Improvements in analytical procedures in parallel with intercalibration of ⁴⁰ Ar/ ³⁹ Ar and U-Pb methods and laboratories, spurred since 2003 by the EarthTime geochronology community initiative, have led to ± 2s uncertainties on the order of 50 to 100 ka, or better for Cretaceous ash beds. Assembled here are fifty-seven ⁴⁰ Ar/ ³⁹ Ar ages and sixtee...
We report the discovery of a Late Cretaceous ammonite, Pseudokossmaticeras brandti, in an archaeological context
at Cueva Tres Bocas de Tanteo, located near the town of Rodas, Cienfuegos Province, in south-central Cuba. The
ammonite manuport is much older than the middle Eocene limestone rock on the cave site and, thus, was likely
transported from...
PDF files are available from the AMNH website:
https://digitallibrary.amnh.org/handle/2246/7319
Understanding the mechanism of selective extinction is important in predicting the impact of anthropogenic environmental changes on current ecosystems. The selective extinction of externally shelled cephalopods at the Cretaceous-Paleogene (K-Pg) mass extinction event (ammonoids versus nautiloids) is often studied, but its mechanism is still debate...
Nautiloids are a charismatic group of marine molluscs best known for their rich fossil record, but today they are restricted to a handful of species in the family Nautilidae from around the Coral Triangle. Recent genetic work has shown a disconnect between traditional species, originally defined on shell characters, but now with new findings from g...
Cephalopod carbonate geochemistry underpins studies ranging from Phanerozoic, global-scale change to outcrop-scale paleoecological reconstructions. Interpreting these data hinges on assumed similarity to model organisms, such as Nautilus , and generalization from other molluscan biomineralization processes. Aquarium rearing and capture of wild Naut...
A bolide impact ~66 million years ago near Chicxulub, Yucatan Peninsula, Mexico triggered environmental perturbations on a global scale, leading to mass extinction at the Cretaceous-Paleogene (K-Pg) boundary. Outcrops on the U.S Gulf Coastal Plain that contain the K-Pg boundary provide a detailed record of environments across this critical transiti...
Hatching size has been considered of great importance in the evolution of externally shelled cephalopods. However, our knowledge of how hatching size varies in response to biotic and abiotic factors is largely lacking. We present a comprehensive overview of hatching size in all known species of modern nautilids (225 specimens, representing eight sp...
A fundamental geochemical process operating at methane seeps is the anaerobic oxidation of methane (AOM) by which methane is oxidized and sulfate is reduced. This process takes place in the sulfate-methane transition zone (SMTZ), generally located below the sediment-water interface. Methane has a low δ13C signature, and this is transferred to the d...
Echinoderms are present, although rare, in Paleozoic, Mesozoic and Cenozoic ancient hydrocarbon seep deposits. They include regular and irregular echinoids, feather star comatulid crinoids, ophiuroids (brittlestars), asteroids (starfish) and stalked crinoids. The rarity of echinoderms may be due to their low preservation potential. However, at some...
Ammonites are present in ancient hydrocarbon seep deposits, ranging from the Devonian to the Cretaceous. The presence of large concentrations of ammonites in a deposit indicates that they were living at the site. This suggests that the depth of the site did not exceed the implosion depth of these cephalopods. The isotopic composition of well-preser...
Modern nautilids ( Nautilus and Allonautilus ) have often been studied by paleontologists to better understand the anatomy and ecology of fossil relatives. Because direct observations of these animals are difficult, the analysis of light stable isotopes (C, O) preserved in their shells has been employed to reveal their habitat and life history. We...
Among the thousands of artifacts recovered in 1891–1892 from Mound 25 of the Middle Woodland Hopewell Mound Group in Ross County, Ohio, is a Cretaceous scaphitid ammonite fossil. We have identified the ammonite as Hoploscaphites brevis, a well-known and well-studied index fossil used to subdivide the Upper Cretaceous deposits of the western interio...
Although soft tissues of coleoid cephalopods record key evolutionary adaptations, they are rarely preserved in the fossil record. This prevents meaningful comparative analyses between extant and fossil forms, as well as the development of a relative timescale for morphological innovations. However, unique 3-D soft tissue preservation of Vampyronass...
We examine temporal and spatial variation in morphology of the ammonoid cephalopod Discoscaphites iris using a large dataset from multiple localities in the Late Cretaceous (Maastrichtian) of the U.S. Gulf and Atlantic Coastal Plains, spanning a distance of 2000 km along the paleoshoreline. Our results suggest that the fossil record of D. iris is c...
We describe an exceptionally well-preserved vampyropod, Syllipsimopodi bideni gen. et sp. nov., from the Carboniferous (Mississippian) Bear Gulch Lagerstätte of Montana, USA. The specimen possesses a gladius and ten robust arms bearing biserial rows of suckers; it is the only known vampyropod to retain the ancestral ten-arm condition. Syllipsimopod...
The giant squid (Architeuthis dux) is the largest living marine invertebrate. Genetic evidence suggests there is a single, globally distributed species. In order to sustain a globally connected population, dispersal of individuals must happen regularly. In many other deep-sea cephalopods, juvenile dispersal though a planktic phase is critical. Alth...
Methane seeps host rich biotic communities, forming patchy yet highly productive ecosystems across the global ocean. Persistent hydrocarbon emissions fuel chemosynthetic food webs at seeps. Methane seeps were abundant in the Western Interior Seaway of North America during the Late Cretaceous. This area also experienced intermittent ash falls, which...
‘Heteromorph ammonoids’ encompass all ammonoid species whose shapes do not
conform to a closely coiled planispiral shell. The term is useful as a broad description
for such ammonoids. However, as a concept, ‘heteromorph ammonoids’ no longer has
any scientific value or explanatory power. Although such ammonoids have traditionally
been considered abe...
Assessing the taxonomic importance of the suture line in shelled cephalopods is a key to better understanding the diversity of this group in Earth history. Because fossils are subject to taphonomic artifacts, an in-depth knowledge of well-preserved modern organisms is needed as an important reference. Here, we examine the suture line morphology of...
Numerous geochemical anomalies exist at the K-Pg boundary that indicate the addition of extraterrestrial materials; however, none fingerprint volatilization, a key process that occurs during large bolide impacts. Stable Zn isotopes are an exceptional indicator of volatility-related processes, where partial vaporization of Zn leaves the residuum enr...
Upper Cretaceous marine sequences in the Gulf Coastal Plain (USA) span the Cretaceous–Paleogene (K–Pg) transition, allowing for detailed studies of one of the most severe extinction events of the Phanerozoic. To improve the temporal resolution of the stratigraphic record that represents environmental change leading up to the K–Pg boundary, we const...
Ammonite soft body remains are rarely preserved. One of the biggest enigmas is the morphology of the ammonite brachial crown that has, up till now, never been recovered. Recently, mysterious hook-like structures have been reported in multiple specimens of Scaphitidae, a large family of heteromorph Late Cretaceous ammonites. A previous examination o...
Methane seep deposits, comprising large, carbonate-rich mounds formed from hydrocarbon seepage, were widely distributed in the Late Cretaceous Western Interior Seaway (WIS) of North America. Well-preserved, methane-derived authigenic carbonates (MDACs) from these deposits have been shown to retain petrological, paleontological, and geochemical impr...
Octopodoidea are a highly versatile and diverse group of marine predators comprising > 200 species today; however, their diversity and ecology in deep time are virtually unknown. Because these soft-bodied cephalopods have a low preservation potential, only a single body fossil species has been documented. Unlike other modern cephalopods, octopodoid...
We report on new collections of cephalopods (ammonites and nautilids) from the Cretaceous-Paleogene (K-Pg) successions of the Corsicana and Kincaid formations exposed along the Brazos River in Falls County, Texas. An abundant fauna of eight species comprising four genera of ammonites is described from the Corsicana Formation, including Discoscaphit...
Methane seeps were a common feature in the Late Cretaceous Western Interior Seaway of the United States. We document the occurrence of methane seep deposits in the Pierre Shale on the Cedar Creek Anticline in east‐central Montana for the first time. The seep deposits occur in the lowermost part of the Baculites baculus Zone (the Endocostea typica Z...
We test for the presence of evolutionary stasis in a species of Late Cretaceous ammonoid cephalopod, Hoploscaphites nicolletii, from the North American Western Interior Seaway. A comprehensive dataset of morphological traits was compiled across the entire spatial and temporal range of this species. These were analysed in conjunction with sedimentol...
The magnitude and ontogenetic patterns of intraspecific variation can provide important insights into the evolution and development of organisms. Understanding the intraspecific variation of organisms is also a key to correctly pursuing studies in major fields of palaeontology. However, intraspecific variation has been largely overlooked in ectococ...
Scaphitid ammonoids were ubiquitous and significant components of the Western Interior Seaway during the Late Cretaceous. This group is characterized by a recurved hook at maturity that deviates from the juvenile whorls. Such a modification seems counterproductive to active locomotion and to manage a biologically effective orientation that facilita...
Cold methane seeps were common in the Late Cretaceous Western Interior Seaway of North America. They provided a habitat for a diverse array of fauna including ammonites. Recent research has demonstrated that ammonites lived at these sites. However, it is still unknown if they hatched at the seeps or only arrived there later in ontogeny. To answer t...
Reconstructing the physiology of extinct organisms is key to understanding mechanisms of selective extinction during biotic crises. Soft tissues of extinct organisms are rarely preserved and, therefore, a proxy for physiological aspects is needed. Here, we examine whether cephalopod conchs yield information about their physiology by assessing how t...
In the last few decades, hook‐like structures have been reported in the Mesozoic ammonite family Scaphitidae. Despite their exceptional preservation and debates about their function, no detailed reconstruction has been available until now. For the first time, we describe the composition and details of the morphology of these structures found in the...
Significance
Debate lingers over what caused the last mass extinction 66 million years ago, with intense volcanism and extraterrestrial impact the most widely supported hypotheses. However, without empirical evidence for either’s exact environmental effects, it is difficult to discern which was most important in driving extinction. It is also uncle...
Coleoidea (squids and octopuses) comprise all crown group cephalopods except the Nautilida. Coleoids are characterized by internal shell (endocochleate), ink sac and arm hooks, while nautilids lack an ink sac, arm hooks, suckers, and have an external conch (ectocochleate). Differentiating between straight conical conchs (orthocones) of Palaeozoic C...
Ammonites are iconic members of Jurassic and Cretaceous marine communities, but many questions remain about their ecology. Because it contains a diverse assemblage of well-preserved macro- and microfossils, the upper Maastrichtian Owl Creek Formation exposed in Tippah County, Mississippi, is an excellent site at which to compare carbonate isotopic...
A lower jaw was recently discovered in a limestone concretion in association with the Late Cretaceous (Turonian) ammonite Spathites puercoensis (Herrick and Johnson, 1900) from the Carlile Member of the Mancos Shale in Sandoval County, New Mexico. It is nearly complete and comprises the aptychus with a hinge along the midline. The better-preserved...
Seep deposits in the Upper Cretaceous US Western Interior appear today as prominent geomorphic features in the landscape and are called “tepee buttes.” They are widespread and occur, in general, from the Campanian to early Maastrichtian, persisting for approximately 7 Myr. The presence of methane has been confirmed by isotopic analyses of the seep...
The Cretaceous/Paleogene boundary section in northwest Morocco is world famous for its vertebrate fossils. However, it also contains abundant ammonites (Baculites anceps). We present a lithostratigraphic and biostratigraphic column based on three sections representing the upper Maastrichtian and lower Paleocene. The sections are mostly composed of...
Two specimens of the Late Mississippian ammonoid cephalopod Metadimorphoceras sp. were recovered from the Bear Gulch Limestone in Montana. This unit was deposited in the lowest part of the Big Snowy Basin, where the bottom waters are thought to have been strongly oxygen deficient. The two nearly equally sized specimens are impressions with soft tis...
This poster provides an overview of the final curation process for the induction of the Royal H. and Gene Mapes Invertebrate Fossil collection to the American Museum of Natural History. This was a Summer Internship program that took place in the summer of 2018.
During the Late Cretaceous most of North America was covered in a broad, shallow epicontinental seaway (the Western Interior Seaway) littered with cold-methane seeps. These unique environments were most common during the middle and late Campanian time period and are concentrated in the northern part of the seaway in modern Montana, Wyoming, and Sou...