Additional Dermal Ossifications in the Anuran Skull: Morphological Novelties or Archaic Elements?

2011 ◽  
Vol 4 (1) ◽  
pp. 17-27 ◽  
Author(s):  
Sergei V. Smirnov
Keyword(s):  
Common Ancestor ◽  
The State ◽  
Cranial Morphology ◽  
Anterior Portion ◽  
Bombina Orientalis ◽  
Common Event ◽  
Rostral Portion ◽  
Morphological Novelties ◽  
Dermal Bones

Examination of the cranial morphology in Bombina orientalis (Anura: Discoglossidae) revealed the occurrence of additional dermal bones lying: a) between the nasals and frontoparietals, b) between frontoparietals, and c) on the tectum synoticum behind the frontoparietals. The presence of similar bones as well as extra ossifications lying in the midline in the rostral portion of skull was shown to be a rather common event among anurans. Based on the occurrence of bones with similar topology in crossopterygians and different stegocephalians, it was concluded that extra ossifications sporadically appearing in anurans are more likely to be ancient cranial elements than neomorphs. Additional dermal bones found in the anterior portion of the anuran skull are homologous to the postrostrals of crossopterygians; extra ossifications lying between the frontoparietals correspond to the bones with similar topology sporadically appearing in crossopterygians and stegocephalians; and extra bones situated behind the frontoparietals are homologous to the lateral extrascapulars (postparietals of stegocephalians) and the median extrascapular of crossopterygians. These extra bones were proposed to be inherited from the presumed common ancestor of all Gnathostomes and retained in anurans in the state of latent capacities. The sporadic appearance of these bones in anurans results from the phenotypical realization of these latent capacities.

scholarly journals Numerical analysis of the characteristics ofCorynebacterium diphtheriaestrains isolated in Victoria from 1962 to 1971

1975 ◽  
Vol 75 (3) ◽  
pp. 413-424
Author(s):  
L. F. Gibson
Keyword(s):  
Numerical Analysis ◽  
Common Ancestor ◽  
Corynebacterium Diphtheriae ◽  
The State ◽  
The Other ◽  
Blood Agar ◽  
Antigenic Structure ◽  
Gradual Change ◽  
Biochemical Activity ◽  
Highly Active

SUMMARYA study of the incidence of diphtheria in the State of Victoria, Australia, was carried out. Numerical analysis of the characteristics of 264 strains ofCorynebacterium diphtheriaeisolated between 1962 and 1971 placed them into 18 varieties plus six strains which were unique in their combination of reactions to the characteristics examined. During the 10-year period, some varieties appeared inter mittently and were recognized by certain defining characteristics but exhibited a gradual change in their antigenic structure. In contrast, when the outbreaks were examined over shorter periods of time, a number of varieties and single strains were found which differed greatly from each other yet possessed the same major serotype antigen. These findings are discussed in terms of a 'one-parent' concept in which the varieties and single strains represent phases of a common ancestor.By inspection and analysis of the characteristics of the strains, certain associations were apparent. For instance, a correlation was found between the antigenic structure of the organism and the colonial appearance on tellurite blood agar. Similarly, correlation was observed between bacteriophage type, diphthericin type and biochemical activity in that a strain which was highly active in one of the properties was also very active in the other two.

scholarly journals Unique Short-Faced Miocene Seal Discovered in Grytsiv (Ukraine)

Zoodiversity ◽  
2021 ◽  
Vol 55 (2) ◽  
pp. 143-154
Author(s):  
I. A. Koretsky ◽  
S. J. Rahmat
Keyword(s):  
Late Miocene ◽  
Phylogenetic Relationships ◽  
Evolutionary History ◽  
Morphological Analysis ◽  
First Record ◽  
Cranial Morphology ◽  
Sea Otter ◽  
Terrestrial Mammal ◽  
Large Size ◽  
Rostral Portion

Numerous Miocene terrestrial mammal fossils have been discovered at the Grytsiv locality of Ukraine, but this is the first record of a fossil marine mammal at this site. Morphological analysis of the rostral portion of this middle-late Miocene (12.3–11.8 Ma) partial skull suggests that it belongs to the subfamily Phocinae. The small size and cranial morphology of this partial skull is compared with recent and fossil representatives of the extant subfamily Phocinae and the extinct subfamily Devinophocinae. Extinct and modern representatives of the extant subfamilies Cystophorinae and Monachinae were not incorporated in this study due to their extremely large size in comparison to this new find. This newly described skull belonged to a small-sized seal (likely similar in size to the modern sea otter based on the width of the rostrum) with an extremely short rostrum and several other diagnostic characters that differ from all other fossil and extant phocines. Due to the lack of preservation and fragility of fossil seal skulls, less than 20 have been described so far. This new skull is yet another example of an ancestral seal, supporting the suggestion that modern seals have become larger over their evolutionary history. Overall, any cranial information on fossil true seals is extremely important since it allows resolving contentious phylogenetic relationships between extinct and extant representatives of this group.

scholarly journals Cryptic transmission of SARS-CoV-2 in Washington State

2020 ◽  
Author(s):  
Trevor Bedford ◽  
Alexander L. Greninger ◽  
Pavitra Roychoudhury ◽  
Lea M. Starita ◽  
Michael Famulare ◽  
...  
Keyword(s):  
Genome Sequencing ◽  
Large Scale ◽  
Common Ancestor ◽  
Genomic Data ◽  
Time Frame ◽  
Washington State ◽  
The State ◽  
Large Majority ◽  
Local Spread ◽  
The World

AbstractFollowing its emergence in Wuhan, China, in late November or early December 2019, the SARS-CoV-2 virus has rapidly spread throughout the world. Genome sequencing of SARS-CoV-2 strains allows for the reconstruction of transmission history connecting these infections. Here, we analyze 346 SARS-CoV-2 genomes from samples collected between 20 February and 15 March 2020 from infected patients in Washington State, USA. We found that the large majority of SARS-CoV-2 infections sampled during this time frame appeared to have derived from a single introduction event into the state in late January or early February 2020 and subsequent local spread, indicating cryptic spread of COVID-19 before active community surveillance was implemented. We estimate a common ancestor of this outbreak clade as occurring between 18 January and 9 February 2020. From genomic data, we estimate an exponential doubling between 2.4 and 5.1 days. These results highlight the need for large-scale community surveillance for SARS-CoV-2 and the power of pathogen genomics to inform epidemiological understanding.

Indirect, across-the-midline retinotectal projections and representation of ipsilateral visual field in superior colliculus of the cat

1978 ◽  
Vol 41 (2) ◽  
pp. 285-304 ◽  
Author(s):  
A. Antonini ◽  
G. Berlucchi ◽  
J. M. Sprague
Keyword(s):  
Visual Field ◽  
Receptive Field ◽  
Superior Colliculus ◽  
Visual Information ◽  
Receptive Fields ◽  
Optic Chiasm ◽  
Anterior Portion ◽  
Vertical Meridian ◽  
Contralateral Eye ◽  
Rostral Portion

1. In agreement with previous work, we have found that the ipsilateral visual field is represented in an extensive rostral portion--from one-third to one-half--of the superior colliculus (SC) of the cat. This representation is binocular. The SC representation of the ipsilateral visual field can be mediated both directly, by crossed retinotectal connections originating from temporal hemiretina, and indirectly, by across-the-midline connections relaying visual information from one-half of the brain to contralateral SC. 2. In order to study the indirect, across-the-midline visual input to the SC, we have recorded responses of SC neurons to visual stimuli presented to either the ipsilateral or the contralateral eye of cats with a midsagittal splitting of the optic chiasm. Units driven by the ipsilateral eye, presumably through the direct retinotectal input and/or corticotectal connections from ipsilateral visual cortex, were found throughout the SC, except at its caudal pole, which normally receives fibers from the extreme periphery of the contralateral nasal hemiretina. Units driven by the contralateral eye, undoubtedly through an indirect across-the-midline connection, were found only in the anterior portion of the SC, in which is normally represented the ipsilateral visual field. Receptive fields in both ipsilateral and contralateral eye had properties typical of SC receptive fields in cats with intact optic pathways. 3. All units having a receptive field in the contralateral eye had also a receptive field in the ipsilateral eye; for each of these units, the receptive fields in both eyes invariably abutted the vertical meridian of the visual field. The receptive field in one eye had about the same elevation relative to the horizontal meridian and the same vertical extension as the receptive field in the other eye; the two receptive fields of each binocular unit matched each other at the vertical meridian and formed a combined receptive field straddling the vertical midline of the horopter...

Cranial morphology and osteology of the sexually dimorphic electric fish, Compsaraia samueli Albert & Crampton (Apteronotidae, Gymnotiformes), with comparisons to C. compsa (Mago-Leccia)

Zootaxa ◽  
2019 ◽  
Vol 4555 (1) ◽  
pp. 101 ◽  
Author(s):  
RACHEL KEEFFE ◽  
ERIC J. HILTON ◽  
MÁRIO J. F. THOMÉ DE SOUZA ◽  
CRISTINA COX FERNANDES
Keyword(s):  
Sexual Dimorphism ◽  
The Body ◽  
Cranial Morphology ◽  
Sexually Dimorphic ◽  
Anterior Portion ◽  
Lower Jaw ◽  
Wide Range ◽  
The Family ◽  
Body Sizes ◽  
Cranial Osteology

Sexual dimorphism of the snout has evolved independently in at least four separate clades of the gymnotiform family Apteronotidae. This phenomenon may help identify sex, except in the absence of mature individuals, and has led to confused taxonomy for several species. We examined a large collection of Compsaraia samueli collected during the breeding season from a remote stream in the Rio Negro drainage. This collection contains a wide range of sizes of both sexes, but most individuals were easily identified as mature. To quantify the sexual dimorphism of these specimens, 15 measurements were taken from the head and the body. In addition, some specimens were cleared-and-stained to study cranial osteology. We found that long-snouted males of C. samueli span a wide range of body sizes. As the snout length increases the distance between the eye and the occiput does not increase at the same rate, suggesting that it is only the anterior portion of the head that has an increased allometry. Skeletal anatomy differs between the sexes in that the lower jaw is more triangular in females and more linear in males. The coronomeckelian is small and round in females in contrast to being longer and pointed in males. There is strong interlacing of the dentary and anguloarticular bones in males, whereas this contact is not as extensive in females. We also discuss the implications of sexual dimorphism for identification of this species relative to its congener (C. compsa), and for the evolution of sexual dimorphism in the family. 

A new species of Cnemaspis Strauch 1887 (Squamata: Gekkonidae) from Pulau Perhentian Besar, Terengganu, Peninsular Malaysia

Zootaxa ◽  
2008 ◽  
Vol 1771 (1) ◽  
pp. 1 ◽  
Author(s):  
L. LEE GRISMER ◽  
CHAN KIN ONN
Keyword(s):  
New Species ◽  
East Coast ◽  
Southeast Asian ◽  
Peninsular Malaysia ◽  
The State ◽  
Anterior Portion ◽  
A New Species

A new species of gekkoind lizard, Cnemaspis perhentianensis sp. nov., is described from Pulau Perhentian Besar, 21 km off the east coast of the state of Terengganu, Peninsular Malaysia. Cnemaspis perhentianensis is differentiated from all other Southeast Asian Cnemaspis in having a maximum SVL of 47.2 mm; the scales of the anterior portion of the forearm are keeled; the ventral scales are weakly keeled; there are no femoral pores; eight preanal pores; there is no linearly arranged row of tubercles on the flanks; there are paravertebral, longitudinal rows of caudal tubercles and lateral caudal rows anteriorly; the keeled subcaudals lack an enlarged median row; there are no large, shield-like subtibial or submetatarsal scales; 28–31 subdigital lamellae are on the fourth toe; distinct, large, dark spots occur on the neck and back that alternate with transverse, white markings; and there are white markings on flanks that alternate with dark blotches.

Functional morphology of the temporal region in the Rhynchocephalia

2003 ◽  
Vol 40 (4) ◽  
pp. 589-607 ◽  
Author(s):  
Xiao-Chun Wu
Keyword(s):  
Functional Morphology ◽  
Common Ancestor ◽  
Lateral Side ◽  
Temporal Region ◽  
Anterior Portion ◽  
Primitive State ◽  
Bone Structures ◽  
Jaw Musculature

Study of the functional morphology of the temporal region of the Rhynchocephalia by means of the analysis of jaw musculature and bone structures in living lepidosaurians suggests that the streptostyly of the quadrate is a derived state in the Lepidosauria and that its origin may have been coupled with the loss of the M. pterygoideus atypicus. Further, this analysis supports the view that the retention of a fixed quadrate in early rhynchocephalians with an incomplete lower temporal bar may have been required for precise tooth occlusion and suggests that a solid lower temporal bar in later rhynchocephalians may have served as a brace to support the lateral side of the quadrate condyle and thus prevent it from twisting anteriorly rather than posteriorly during the jaw cycle. It is hypothesized that a common ancestor shared by the Rhynchocephalia and Squamata had a skull with an incomplete lower temporal bar but a rigid quadrate. It is also hypothesized that the presence of the anterior portion of the M. pterygoideus (MPT) is a primitive state, and that the size of the pterygoid flange may have been a good indicator of the presence of the anterior portion of the MPT in fossil reptiles. As in Sphenodon, if the mandible is able to move anteroposteriorly, it must retract first during the jaw cycle in those reptiles in which a pterygoid flange is retained.

A new species of karst dwelling gecko (genus Cnemaspis Strauch 1887) from the border region of Thailand and Peninsular Malaysia

Zootaxa ◽  
2008 ◽  
Vol 1875 (1) ◽  
pp. 51 ◽  
Author(s):  
L. LEE GRISMER ◽  
CHAN KIN ONN ◽  
NUROLHUDA NASIR ◽  
MONTRI SUMONTHA
Keyword(s):  
New Species ◽  
Southeast Asian ◽  
Peninsular Malaysia ◽  
The State ◽  
Border Region ◽  
Large White ◽  
Anterior Portion ◽  
Southern Thailand ◽  
A New Species

A new species of karst dwelling gecko, Cnemaspis biocellata sp. nov. is described from the border region in the Satun Province of southern Thailand and the state of Perlis in northern Peninsular Malaysia. Cnemaspis biocellata sp. nov. is differentiated from all other species of Southeast Asian Cnemaspis by having a maximum SVL of 40.1 mm; 6–10 supralabials; 5–7 infralabials; weakly keeled scales on anterior portion of forearm; smooth ventral scales; no femoral pores; 8–12 precloacal pores; smooth subcaudals with an enlarged median row; one or two cloacal tubercles; 29–37 subdigital lamellae on fourth toe; no dark bands encircling tail; two distinct, white, well defined, occipital ocelli; a black occipital band bordering a series of closely spaced, large, white to yellow spots which form a nuchal band and a small, black shoulder patch enclosing a single white to yellow ocellus. This species is restricted to the karst formations of the Nakawan Range spanning the Thai-Malaysian border and has been misidentified as C. siamensis by previous authors.

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