scholarly journals Cranial anatomy of Allosaurus jimmadseni, a new species from the lower part of the Morrison Formation (Upper Jurassic) of Western North America

PeerJ ◽  
2020 ◽  
Vol 8 ◽  
pp. e7803 ◽  
Author(s):  
Daniel J. Chure ◽  
Mark A. Loewen

Allosaurus is one of the best known theropod dinosaurs from the Jurassic and a crucial taxon in phylogenetic analyses. On the basis of an in-depth, firsthand study of the bulk of Allosaurus specimens housed in North American institutions, we describe here a new theropod dinosaur from the Upper Jurassic Morrison Formation of Western North America, Allosaurus jimmadseni sp. nov., based upon a remarkably complete articulated skeleton and skull and a second specimen with an articulated skull and associated skeleton. The present study also assigns several other specimens to this new species, Allosaurus jimmadseni, which is characterized by a number of autapomorphies present on the dermal skull roof and additional characters present in the postcrania. In particular, whereas the ventral margin of the jugal of Allosaurus fragilis has pronounced sigmoidal convexity, the ventral margin is virtually straight in Allosaurus jimmadseni. The paired nasals of Allosaurus jimmadseni possess bilateral, blade-like crests along the lateral margin, forming a pronounced nasolacrimal crest that is absent in Allosaurus fragilis.

2011 ◽  
Vol 85 (1) ◽  
pp. 102-105 ◽  
Author(s):  
Dena M. Smith ◽  
Mark A. Gorman ◽  
Jason D. Pardo ◽  
Bryan J. Small

A new species of Orthoptera,Parapleurites morrisonensis, is described from the upper Jurassic Morrison Formation of Colorado, USA. This is the first insect described from the Morrison Formation and the first orthopteran described from the Jurassic of North America. No other members of the family Locustopsidae have been described in North America previously, and the other species ofParapleuritesare only known from Siberia. The lack of Jurassic Orthoptera in North America is likely due to a combination of taphonomic variables and collector bias. The discovery ofParapleurites morrisonensisand the potential for finding other Jurassic Orthoptera are important to understanding the evolution of this diverse and widely distributed group.


2021 ◽  
Vol 97 (1) ◽  
pp. 223-233
Author(s):  
Yusuke Sugawara ◽  
Yoh Ihara ◽  
Takafumi Nakano

Spiders of the genus Cybaeus L. Koch, 1868 exhibit two major centers of diversity: Western North America and Japan. Several Japanese Cybaeus possess an elongated embolus in the male palp and elongated tubular spermathecae in the female genitalia. Here we describe Cybaeus koikeisp. nov. from central Honshu, Japan, which has an unelongated embolus and bulbous spermathecae. Phylogenetic analyses using nuclear and mitochondrial gene markers clearly support the monophyly of C. koikeisp. nov. and Cybaeus melanoparvus Kobayashi, 2006, a species with elongated genitalia. Both species share a similar habitus and a cluster of robust setae on the lateral surface of the male palpal patella. The latter is considered a synapomorphy for C. koikeisp. nov. and C. melanoparvus. A supplementary description of the spermathecae of C. melanoparvus is also provided.


1964 ◽  
Vol 96 (3) ◽  
pp. 522-528 ◽  
Author(s):  
G. R. Underwood ◽  
R. E. Balch

AbstractA new anholocyclic species from the coastal region of western North America on Abies amabilis (Dougl.) Forbes and A. grandis (Dougl.) Lindl. is described. This is the first species of Pineus found on true firs.


1964 ◽  
Vol 21 (5) ◽  
pp. 933-939 ◽  
Author(s):  
Richard H. Rosenblatt

A new species, Pholis clemensi, referred to the family Pholidae, is named and described from 12 specimens taken in southern British Columbia waters and the Strait of Juan de Fuca. Pholis clemensi is compared with other members of the genus, and a key is given to the North American species.


1956 ◽  
Vol 13 (4) ◽  
pp. 541-546 ◽  
Author(s):  
E. Berkeley ◽  
C. Berkeley

Records are given of two species and a variety new to western Canada and notes on three other species already known from the region. A new species, Aricidea lopezi, and four species new to western North America, are described from the neighbourhood of Friday Harbour, Washington.


1982 ◽  
Vol 114 (11) ◽  
pp. 1077-1082 ◽  
Author(s):  
H. J. Teskey

AbstractHybomitra enigmatica n. sp., previously confused with Hybomitra sonomensis (O.S.), is described in larval, pupal, and adult stages and compared with the latter species and with H. phaenops (O.S.). Hybomitra philipi Stone is synonymized with H. sonomensis. The distribution of these species in western North America is given.


1963 ◽  
Vol 41 (1) ◽  
pp. 115-124 ◽  
Author(s):  
Larry S. Roberts

A new species of parasitic copepod occurring in western North America is described, Ergasilus nerkae n. sp. An emendation of E. turgidus Fraser, 1920 and a redescription of E. auritus Markevich, 1940 are presented. A total of four species resembling E. caeruleus (E. turgidus, E. confusus Bere, 1931, E. auritus, and E. nerkae) have so far been described, and characters to distinguish the species of this group are given.


1983 ◽  
Vol 115 (6) ◽  
pp. 693-702 ◽  
Author(s):  
H. J. Teskey

AbstractDescribed are adults of Atylotus insuetus (Osten Sacken), A. calcar n. sp., A. utahensis (Rowe and Knowlton) and A. tingaureus (Philip) and immature stages of the first two species. The distribution of the four species in western North America is plotted and a key is provided for their separation.


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