Linked Life Data

6644822

Source:http://linkedlifedata.com/resource/pubmed/id/6644822

Statements in which the resource exists as a subject.
PredicateObject
rdf:type
lifeskim:mentions
pubmed:issue
3
pubmed:dateCreated
1984-1-7
pubmed:abstractText
Relative size and arrangement of the brain and paired sense organs are examined in three species of Thorius, a genus of minute, terrestrial salamanders that are among the smallest extant tailed tetrapods. Analogous measurements of representative species of three related genera of larger tropical (Pseudoeurycea, Chiropterotriton) and temperate (Plethodon) salamanders are used to identify changes in gross morphology of the brain and sense organs that have accompanied the evolution of decreased head size in Thorius and their relation to associated changes in skull morphology. In adult Thorius, relative size (area measured in frontal plane, and length) of the eyes, otic capsules, and brain each is greater than in adults of all of the larger genera; relative size of the nasal capsules is unchanged or slightly smaller. Interspecific scaling phenomena--negative allometry of otic capsule, eye and brain size, isometry or slight positive allometry of nasal capsule size, all with respect to skull length--also are characteristic of intraspecific (ontogenetic) comparisons in both T. narisovalis and Pseudoeurycea goebeli. Predominance of the brain and eyes in Thorius results in greater contact and overlap among these structures and the nasal capsules in the anterior portion of the head. This is associated with anterior displacement of both the eyes and nasal capsules, which now protrude anterior to the skull proper; a change in eye shape; and medial deformation of anterior braincase walls. Posteriorly, predominance of the otic capsules has effected a reorientation of the jaw suspensorium to a fully vertical position that is correlated with the novel presence of a posteriorly directed squamosal process and shift in origin of the quadropectoralis muscle. Many of these changes in cranial morphology may be explained simply as results of mechanical (physical) interactions among the skeletal, nervous, and sensory components during head development at reduced size. This provides further evidence of the role of nervous, sensory, and other "soft" tissues in cranial skeletal morphogenesis, and reinforces the need to consider these tissues in analyses of skull evolution.
pubmed:language
eng
pubmed:journal
pubmed:citationSubset
IM
pubmed:status
MEDLINE
pubmed:month
Sep
pubmed:issn
0362-2525
pubmed:author
pubmed:issnType
Print
pubmed:volume
177
pubmed:owner
NLM
pubmed:authorsComplete
Y
pubmed:pagination
255-68
pubmed:dateRevised
2010-11-18
pubmed:meshHeading
pubmed:year
1983
pubmed:articleTitle
Miniaturization and its effects on cranial morphology in plethodontid salamanders, genus Thorius (Amphibia, Plethodontidae): II. The fate of the brain and sense organs and their role in skull morphogenesis and evolution.
pubmed:publicationType
Journal Article, Comparative Study, Research Support, U.S. Gov't, Non-P.H.S., Research Support, Non-U.S. Gov't