A Middle Pleistocene Sea Otter from Northern California and the Antiquity of Enhydra in the Pacific Basin

Boessenecker, Robert W.

doi:10.1007/s10914-016-9373-6

Cited by 11 publications

(7 citation statements)

References 29 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…A late Pliocene age was assigned to the Fernando and Niguel Formations based on foraminiferal biostratigraphy (Schoellhamer et al, 1981). Strontium isotope analysis of foraminifera in the Merced Formation yielded ages of 3.6-0.62 Ma (Ingram and Ingle, 1998;Boessenecker, 2018). Radiometric dates from tephra layers have constrained the Purisima Formation to between 6.9 Ma and 3.3 Ma (Powell et al, 2007), while a combination of lithostratigraphic, biostratigraphic, and chronostratigraphic data constrained the age of the San Joaquin Formation to between 5.3 Ma and 2.2 Ma (Bowersox, 2006).…”

Section: Geological Setting and Previous Age Determinationsmentioning

confidence: 99%

On the reconciliation of biostratigraphy and strontium isotope stratigraphy of three southern Californian Plio-Pleistocene formations

et al. 2020

View full text Add to dashboard Cite

The San Diego Formation, Pico Formation, Careaga Sandstone, and Foxen Mudstone of southern California are thought to be late Pliocene to early Pleistocene; however, numerical ages have not been determined. Following assessment of diagenetic alteration via multiple methods including scanning electron microscopy (SEM), X-ray diffraction (XRD), and minor elemental concentrations, we attempted to use strontium isotope stratigraphy to assign numerical ages. Using aragonitic fossils, we obtained ages of 2.0−1.85 Ma for the Careaga Sandstone and 2.0−1.75 Ma for the uppermost Foxen Mudstone, consistent with biostratigraphic work suggesting a Gelasian age for the Careaga Sandstone. Isotope ratios for aragonitic and calcitic fossils from the Pico Formation were poorly constrained, with the exception of one bed yielding ages of 5.1−4.3 Ma. Isotope ratios from the San Diego Formation were also inconsistent within beds, with the exception of two isolated outcrops that yielded ages of 5.0−4.5 Ma and 4.5−2.8 Ma, respectively. The age estimates for the Pico and San Diego Formations are older than most ages inferred from biostratigraphy. Noting that some aragonitic specimens from the San Diego Formation yielded isotope ratios indicative of ages as old as 19.4 Ma, we propose that some outcrops have been affected by diagenesis caused by groundwater flow through proximal granitic rocks and input from detrital sediment. Although we recommend that strontium isotope results for the Pico and San Diego Formations be interpreted with caution, the ages of the uppermost Foxen Mudstone and Careaga Sandstone can be confidently placed within the early Pleistocene.

show abstract

Section: Geological Setting and Previous Age Determinationsmentioning

confidence: 99%

On the reconciliation of biostratigraphy and strontium isotope stratigraphy of three southern Californian Plio-Pleistocene formations

et al. 2020

View full text Add to dashboard Cite

show abstract

“…In contrast, our discovery of Enhydritherium in central Mexico suggests that a land-based route was much more likely, in terms of shorter distance (less than 4000 km), and is supported by fossils from an entirely land-locked basin containing upper Miocene fluviolacustrine deposits [6]. A recent study of fossil Enhydra records indicates that sea otters may have dispersed into the eastern Pacific from the North Atlantic not much earlier than middle Pleistocene [3]; this biogeographic scenario, plus recent cladistics analyses indicating a distant relationship between Enhydritherium and extant sea otters [4], and the new fossil evidence presented in this report, together suggest that the previously proposed close relationship between Enhydra and Enhydritherium is not supported [8].…”

Section: Resultsmentioning

confidence: 96%

“…Although ocean-going otters had to have evolved from freshwater ancestors [2], the fossil record of the North American sea otters is poor, and the evolutionary origin of extant sea otters remains uncertain [3]. Recent phylogenetic analyses of morphological and genetic sequence data suggest that Enhydra is most closely related to Asian fossil otters, whereas earlier palaeontological analyses indicate a close relationship between Enhydra and the fossil otter Enhydritherium terraenovae [4].…”

Section: Introductionmentioning

confidence: 99%

Discovery of the fossil otter Enhydritherium terraenovae (Carnivora, Mammalia) in Mexico reconciles a palaeozoogeographic mystery

et al. 2017

View full text Add to dashboard Cite

The North American fossil otter is thought to be partially convergent in ecological niche with the living sea otter, both having low-crowned crushing teeth and a close association with marine environments. Fossil records of are found in mostly marginal marine deposits in California and Florida; despite presence of very rich records of fossil terrestrial mammals in contemporaneous localities inland, no fossils are hitherto known in interior North America. Here we report the first occurrence of outside of Florida and California, in a land-locked terrestrial mammal fauna of the upper Miocene deposits of Juchipila Basin, Zacatecas State, Mexico. This new occurrence of is at least 200 km from the modern Pacific coastline, and nearly 600 km from the Gulf of Mexico. Besides providing further evidence that was not dependent on coastal marine environments as originally interpreted, this discovery leads us to propose a new east-to-west dispersal route between the Florida and California populations through central Mexico. The proximity of the fossil locality to nearby populations of modern neotropical otters suggests that trans-Mexican freshwater corridors for vertebrate species in riparian habitats may have persisted for a prolonged period of time, pre-dating the Great American Biotic Interchange.

show abstract

“…A rise in sea level may have been involved in the Mio-Pliocene extinction of phocids in South America, resulting in the decrease of sandy beach haul-out areas favored by phocids. Beginning in the Plio-Pleistocene and continuing at present, rocky shore habitats predominated in South America and elsewhere in the Southern Hemisphere (e.g., Africa, Oceania), areas exclusively occupied by otariids (Valenzuela-Toro et al, 2013, 2016. This hypothesis of ecological replacement of phocids by otariids is difficult to confirm at the present time since marine mammal fossils in South America are relatively poorly known and not well sampled during this time.…”

Section: Diversity Through Timementioning

confidence: 93%

“…The oldest record of Enhydra sp. from the Pacific is Middle Pleistocene in age although an earlier representative of this lineage (Enhydra reevei) arose in the North Atlantic during the early Pleistocene about 2.2-1.7 Ma and presumably dispersed into the Pacific though the Bering Strait (Boessenecker, 2016). The extinct sea mink Neovison macrodon known from the early to Late Pleistocene in marine and estuarine habitats along the coastal islands of the Gulf of Maine was hunted to extinction, a victim of the fur trade in the late 1800s (Mead et al, 2000).…”

Section: Diversity Through Timementioning

confidence: 99%

Feeding in marine mammals: An integration of evolution and ecology through time

Berta

Lanzetti

2020

Palaeontol Electron

View full text Add to dashboard Cite

Marine mammals are key components of aquatic ecosystems. Feeding strategies identified in extant cetaceans, pinnipeds, sirenians, marine otters, and polar bears are associated with anatomical specializations of the head (rostrum, palate, temporomandibular joint, teeth/baleen, mandible). Genetic and ontogenetic evidence of skull and tooth morphology provide the mechanisms that underlie patterns of feeding diversity. Based on a comprehensive diversity data set derived from the Paleobiology Database, we considered feeding strategies (suction, biting, filter feeding, grazing), prey type (squid, fish, benthic invertebrates, zooplankton, tetrapods, sea grasses), tooth pattern and cusp shape (homodont, heterodont, pointed, rounded, edentulous), and habitat (marine, riverine, estuarine) in fossil and extant marine mammals. These variables were then tested for correlation and their changes through time examined in relation to productivity and climate variables. We provide an integrated analysis of the evolution of feeding and trophic structure in marine mammals and explore the origin and timing of particular feeding strategies over the last 50 million years. In agreement with earlier reports, updated generic counts reveal that the greatest diversity of pinnipedimorphs and cetaceans occurred during the late Miocene (Tortonian), following the Mid-Miocene Climatic Optimum. These historical data are used as a framework to inform past and present structure and trophic interactions and enable predictions about future marine ecosystems.The drivers of diet and feeding patterns are both environmental (sea level fluctuations, climate change) and biotic (anatomical specializations, competition, predator-prey). The influence of these processes on paleodiversity varies depending on taxonomic group, timing, and geographic scale.

show abstract

A Middle Pleistocene Sea Otter from Northern California and the Antiquity of Enhydra in the Pacific Basin

Cited by 11 publications

References 29 publications

On the reconciliation of biostratigraphy and strontium isotope stratigraphy of three southern Californian Plio-Pleistocene formations

On the reconciliation of biostratigraphy and strontium isotope stratigraphy of three southern Californian Plio-Pleistocene formations

Discovery of the fossil otter Enhydritherium terraenovae (Carnivora, Mammalia) in Mexico reconciles a palaeozoogeographic mystery

Feeding in marine mammals: An integration of evolution and ecology through time

Contact Info

Product

Resources

About