Positional and ontogenetic variation in vertebral centra morphology in five batoid species

2020 ◽  
Author(s):  
Kelsey C. James ◽  
Lisa J. Natanson
Keyword(s):  
Ontogenetic Variation ◽  
Vertebral Centra

ONTOGENETIC VARIATION ON CRANIDIAL SHAPE OF THE LATE MIDDLE CAMBRIAN (CAMBRIAN SERIES 3) TRILOBITE JIULONGSHANIA ACALLA

2018 ◽  
Author(s):  
Shujian Qin ◽  
◽  
Lin Dong ◽  
Bing Shen
Keyword(s):  
Ontogenetic Variation ◽  
Middle Cambrian

Morphology and diet of two sympatric colubrid snakes, Chironius flavolineatus and Chironius quadricarinatus (Serpentes: Colubridae)

2008 ◽  
Vol 29 (2) ◽  
pp. 149-160 ◽  
Author(s):  
Otavio Augusto Vuolo Marques ◽  
Ronaldo Fernandes ◽  
Roberta Richard Pinto
Keyword(s):  
Foraging Behaviour ◽  
Sexual Size Dimorphism ◽  
Sympatric Species ◽  
Colour Pattern ◽  
Ontogenetic Variation ◽  
Brazilian Cerrado ◽  
Size Dimorphism ◽  
Snake Species ◽  
Dietary Ecology ◽  
Arboreal Habit

Abstract The morphometry and diet of two sympatric species of Chironius (C. flavolineatus and C. quadricarinatus) from Brazilian Cerrado are described. The two snake species differ in external morphology, as Chironius flavolineatus was the largest species (body, tail and eyes) whereas C. quadricarinatus the heaviest. Each species also showed marked sexual size dimorphism. In terms of dietary ecology, both species feed exclusively on frogs with a heavy preference for hylids and may have tendency to eat small items, as noticed in other colubrine species. These two snake species showed a brownish colour pattern and exhibited no ontogenetic variation, suggesting that juveniles and adults use similar substrates. Chironius flavolineatus and C. quadricarinatus present a semi-arboreal habit, with active foraging behaviour, feeding in the ground most of time. Chironius flavolineatus uses higher vegetation for resting and, based on morphological results, seems to be more arboreal than C. quadricarinatus.

Ontogenetic variation of trophic habitat for sympatric benthic octopods in East China Sea derived from isotopic analysis on beaks

2021 ◽  
Vol 238 ◽  
pp. 105902
Author(s):  
Zhou Fang ◽  
Peiwu Han ◽  
Siwenjia Shi ◽  
Xinjun Chen
Keyword(s):  
East China Sea ◽  
Isotopic Analysis ◽  
East China ◽  
Ontogenetic Variation ◽  
China Sea

scholarly journals Sexual dimorphism and ontogenetic variation in the carapace ofA. pallipes(Lereboullet, 1858)

2009 ◽  
Vol 76 (2) ◽  
pp. 179-188 ◽  
Author(s):  
M. Scalici ◽  
G. Gibertini
Keyword(s):  
Sexual Dimorphism ◽  
Ontogenetic Variation

Ecology and Ontogenetic Variation of Diet in the Pigmy Short-Horned Lizard (Phrynosoma Douglasii)

2008 ◽  
Vol 159 (2) ◽  
pp. 327-339 ◽  
Author(s):  
Megan E. Lahti ◽  
Daniel D. Beck
Keyword(s):  
Ontogenetic Variation

scholarly journals Questioning hagfish affinities of the enigmatic Devonian vertebrate Palaeospondylus

2017 ◽  
Vol 4 (7) ◽  
pp. 170214 ◽  
Author(s):  
Zerina Johanson ◽  
Moya Smith ◽  
Sophie Sanchez ◽  
Tim Senden ◽  
Kate Trinajstic ◽  
...  
Keyword(s):  
Semicircular Canals ◽  
Crown Group ◽  
Vertebral Centra ◽  
Stem Group ◽  
Tomographic Data

Palaeospondylus gunni Traquair, 1890 is an enigmatic Devonian vertebrate whose taxonomic affinities have been debated since it was first described. Most recently, Palaeospondylus has been identified as a stem-group hagfish (Myxinoidea). However, one character questioning this assignment is the presence of three semicircular canals in the otic region of the cartilaginous skull, a feature of jawed vertebrates. Additionally, new tomographic data reveal that the following characters of crown-group gnathostomes (chondrichthyans + osteichthyans) are present in Palaeospondylus : a longer telencephalic region of the braincase, separation of otic and occipital regions by the otico-occipital fissure, and vertebral centra. As well, a precerebral fontanelle and postorbital articulation of the palatoquadrate are characteristic of certain chondrichthyans. Similarities in the structure of the postorbital process to taxa such as Pucapampella , and possible presence of the ventral cranial fissure, both support a resolution of Pa. gunni as a stem chondrichthyan. The internally mineralized cartilaginous skeleton in Palaeospondylus may represent a stage in the loss of bone characteristic of the Chondrichthyes.

Age and growth of the shortfin mako (Isurus oxyrinchus) in the south-eastern Pacific off Chile

2009 ◽  
Vol 60 (5) ◽  
pp. 394 ◽  
Author(s):  
Francisco Cerna ◽  
Roberto Licandeo
Keyword(s):  
Growth Parameters ◽  
Eastern Pacific ◽  
Age And Growth ◽  
The South ◽  
Age Classes ◽  
Vertebral Centra ◽  
South Eastern ◽  
Isurus Oxyrinchus ◽  
Shortfin Mako ◽  
Longline Fisheries

The shortfin mako, Isurus oxyrinchus, is a large pelagic shark with a widespread global distribution. However, very little is known about most aspects of this species for the south-eastern Pacific. In the present paper, the age and growth parameters of the shortfin mako, caught by Chilean swordfish longline fisheries from 2004 to 2005, are reported. Ages were estimated by counting band-pairs from sections of vertebral centra from 547 individuals, ranging from 76 to 330 cm in total length (TL). Trends in the proportion of opaque edges for all ages combined and grouped into ages 0–6 and 7–26 years indicated that they are formed during summer and showed that annually, one band-pair is formed in the vertebrae of shortfin makos. Modal-progression analysis was used to verify the first three age classes (ages 0–2 years). For both sexes, the oldest estimated age was 25+ years. Von Bertalanffy growth parameters were estimated at L∞ = 325.29 cm TL, K = 0.076 year–1 and t0 = –3.18 years for females and L∞ = 296.60 cm TL, K = 0.087 year–1 and t0 = –3.58 years for males. The results indicated that this species is highly vulnerable to exploitation and, thus, urgent conservation measures are required.

Ontogenetic variation in human nasal morphology

2021 ◽  
Author(s):  
Lauren N. Butaric ◽  
Christina L. Nicholas ◽  
Katherine Kravchuk ◽  
Scott D. Maddux
Keyword(s):  
Ontogenetic Variation

Systematic revision of the flatfish genus Peltorhamphus Günther, 1862 (Teleostei: Pleuronectiformes: Rhombosoleidae), including description of a new species from Southeastern New Zealand, with biological and ecological summaries for the species

Zootaxa ◽  
2021 ◽  
Vol 4905 (1) ◽  
pp. 1-104
Author(s):  
THOMAS A. MUNROE
Keyword(s):  
New Zealand ◽  
Lower Limb ◽  
Ontogenetic Variation ◽  
Ventral Margin ◽  
Blind Side ◽  
Ocular Side ◽  
Lower Jaw ◽  
Interorbital Width ◽  
Fin Ray ◽  
Deep Body

The flatfish genus Peltorhamphus Günther, 1862 (Pleuronectiformes: Rhombosoleidae) and its constituent species are redescribed based on examination of 1885 specimens. Four species are considered valid: three previously described (P. novaezeelandiae Günther, 1862, P. latus James, 1972, and P. tenuis James, 1972) and P. kryptostomus n. sp., described herein. Peltorhamphus novaezeelandiae, P. latus, and P. tenuis have widespread distributions on soft sediments in shallow coastal and inner continental shelf waters off both islands of New Zealand. Peltorhamphus novaezeelandiae has also been reported at the Chatham Islands. Previous reports of P. novaezeelandiae from Norfolk Island are erroneous. Peltorhamphus kryptostomus n. sp. has the most restricted geographic distribution in shallow coastal waters of the Otago-Southland region along the southeastern coast of South Island. The four species of Peltorhamphus are morphologically similar and overlap in many traditional meristic and morphometric features rendering identifications difficult, especially of juveniles and earlier life-history stages. Furthermore, throughout New Zealand waters, as many as three of the species possibly occur sympatrically, while in inshore areas of southeastern South Island, all four species may occur in sympatry. Novel morphological characters discovered in this study, combined with traditional diagnostic characters were used to identify and diagnose the species. Peltorhamphus tenuis is the most distinctive of the four, differing from congeners in the following combination of characters: greater length of second ocular-side pectoral-fin ray; its higher numbers of dorsal- and anal-fin rays and total vertebrae; having a series of small scales (best developed in specimens >70 mm SL) on blind sides of dorsal- and anal-fin rays (scales absent in congeners); its elongate body; and ocular-side pigmentation. The other three species are more similar morphologically and have frequently been misidentified both in fish collections and in some previous literature on these fishes. Of these three, P. novaezeelandiae, the largest in the genus, is distinguished from congeners by the combination of: its large size (reaching 510 mm SL vs. ≤ 200 mm SL); rounded head shape; blind-side squamation; the second ocular-side pectoral-fin ray shorter than body depth; ontogenetic variation in interorbital width; greater distance (4–8 scales wide) between ventral margin of lower eye and dorsal (upper) margin of rostral hood above the mouth; and 2–6 fleshy, finger-like filaments on the inner anteroventral margin of the fleshy skinfold on the ocular-side lower jaw. Peltorhamphus latus differs from congeners by the combination of: its short (maximum 150 mm SL), relatively deep body and bluntly pointed snout; blind-side squamation; relatively long, robust gillrakers on first gill arch, with upper limb gillrakers long, but not usually overlapping tips of dorsalmost gillrakers on the lower limb; black pigment on entire roof of mouth; relatively large eyes and narrow interorbital width (without significant ontogenetic variation); short diagonal distance (usually 2–3 scales wide) between ventral margin of lower eye and dorsal (upper) margin of rostral hood above the mouth; and absence of finger-like filaments on the inner anteroventral margin of the fleshy skinfold on the ocular-side lower jaw. Peltorhamphus kryptostomus n. sp. is distinguished from congeners by the combination of: its deep body and smoothly rounded snout; blind-side squamation; long, robust gillrakers on the first gill arch, with some posterior gillrakers on the upper limb overlapping tips of the first and second dorsalmost gillrakers on the lower limb; black pigment on the entire roof of the mouth; relatively large eyes and relatively narrow interorbital width; wide distance between ventral margin of lower eye and upper margin of rostral hood (3–6, usually 4–5, scales wide); and 1–4 finger-like filaments on the inner anteroventral margin of the fleshy skinfold on the ocular-side lower jaw. Ecological and life-history information are summarized for each species, and a key to juveniles > 40 mm SL and adults is also provided. Re-assessment of the number of valid species of Peltorhamphus provides better understanding of species diversity within this genus and within the Rhombosoleidae, as well as that for the flatfish assemblage residing in New Zealand waters. 

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