The largest mosasaur (Squamata: Mosasauridae) from the Missouri River area (Late Cretaceous; Pierre Shale Group) of South Dakota and its relationship to Lewis and Clark

2007 ◽  
Author(s):  
Robert W. Meredith ◽  
James E. Martin ◽  
Paul N. Wegleitner
Keyword(s):  
South Dakota ◽  
Late Cretaceous ◽  
Missouri River ◽  
Pierre Shale ◽  
Lewis And Clark

Osteology and taxonomy of Mosasaurus conodon Cope 1881 from the Late Cretaceous of North America

2014 ◽  
Vol 94 (1) ◽  
pp. 39-54 ◽  
Author(s):  
T. Ikejiri ◽  
S.G. Lucas
Keyword(s):  
North America ◽  
South Dakota ◽  
Late Cretaceous ◽  
Lower Number ◽  
Junior Synonym ◽  
Morphological Data ◽  
Length Ratio ◽  
Nominal Species ◽  
European Species ◽  
Pierre Shale

AbstractTwo well-preserved skeletons of Mosasaurus conodon Cope 1881 (Squamata, Mosasaurinae) from the Pierre Shale (late Campanian) of Colorado and the Bearpaw Shale (Late Campanian to Early Maastrichtian) of Montana are described. The two specimens are important because they provide new osteological information, especially on the skull (including jaws with teeth) and forelimbs, whereas those elements are largely missing in the holotype (AMNH 1380) of M. conodon. Morphological comparisons of the holotype with the two new specimens allow us to emend the diagnosis of the species in the genus Mosasaurus, primarily using tooth and forelimb morphologies. Teeth of M. conodon are unique in their combination of having a slender, gently recurved overall shape (similar to Clidastes) with no serration on the developed carinae (less developed in Clidastes). The tooth count of M. conodon tends to be low (14–15 in the maxilla, 16 in the dentary and eight in the pterygoid, respectively) when compared to other species, such as Mosasaurus lemonnieri, Mosasaurus missouriensis and Mosasaurus hoffmanni–Mosasaurus maximus. The forelimb is short in the species, characterised by a much lower number of the manual digital formula, 4(+1?)–4(+2?)–4(+1?)–4(+1)–2 than other species of Mosasaurus. The forelimb bones are generally robust, especially the box-shaped humerus (width-to-length ratio 3/2). A variety of new morphological data support the conclusions that (1) M. conodon is a nominal species, (2) the European species M. lemonnieri is not a junior synonym and (3) one of the most complete skeletons of Mosasaurus from South Dakota (SDSM 452) is not assigned to M. conodon (but is likely to be Mosasaurus sp.). To date, M. conodon occurs only in North America during the late Campanian to early Maastrichtian.

scholarly journals Factors related to age-0 native fish catch per unit effort in the South Dakota Missouri River reservoirs.

2020 ◽  
Author(s):  
William Radigan ◽  
Mark Fincel
Keyword(s):  
South Dakota ◽  
Fish Species ◽  
Native Species ◽  
Abiotic Factors ◽  
Missouri River ◽  
Native Fish ◽  
Catch Per Unit Effort ◽  
Biotic And Abiotic Factors ◽  
Emerald Shiner ◽  
Lewis And Clark

The Missouri River in South Dakota was dammed in the 1950s and 1960s, altering the biotic and abiotic factors that potentially affect native species in the mainstem reservoirs. Little research has been conducted regarding what factors regulate age-0 CPUE (catch per unit effort) of native fish species since the damming occurred. Thus, we examined age-0 CPUE for thirteen native fish species in the four Missouri River mainstem reservoirs. We analyzed data from 1995-2015 in Lake Oahe, 2002-2016 in Lake Sharpe, 1998-2008 in Lake Francis Case, and 2000-2013 in Lewis and Clark Lake. Not all species were sampled in all reservoirs. We evaluated potential environmental (inflow, gauge height, peak flow, precipitation, air temperature) and biological (CPUE of other native species, non-native CPUE, predator CPUE) factors that have documented impacts on age-0 native fish CPUE. Significant relationships existed between age-0 native fish CPUE and both biotic and abiotic factors in all four reservoirs, but specific factors related to native fish CPUE were species and reservoir dependent. For all species examined in all reservoirs except age-0 Emerald Shiner Notropis atherinoides CPUE in Lewis and Clark Lake, age-0 CPUE was either stable or increasing. Age-0 Emerald Shiner CPUE in Lewis and Clark Lake was most supported by total age-0 non-native CPUE and adult White Bass Morone chrysops CPUE, and a positive relationship existed between age-0 Emerald Shiner CPUE and both factors. We believe our findings provide valuable insight into successful management of native fish populations.

Sign in / Sign up

Export Citation Format

Share Document