scholarly journals Bias in interspecific allometry: examples from morphological scaling in varanid lizards

2009 ◽  
Vol 96 (2) ◽  
pp. 296-305 ◽  
Author(s):  
GARY C. PACKARD ◽  
THOMAS J. BOARDMAN
Keyword(s):  
Interspecific Allometry

scholarly journals Modeling the physiology of the aquatic temnospondyl <i>Archegosaurus decheni</i> from the early Permian of Germany

Fossil Record ◽  
2017 ◽  
Vol 20 (2) ◽  
pp. 105-127 ◽  
Author(s):  
Florian Witzmann ◽  
Elizabeth Brainerd
Keyword(s):  
Metabolic Rate ◽  
Body Length ◽  
Lung Ventilation ◽  
Standard Metabolic Rate ◽  
Nitrogen Excretion ◽  
Early Permian ◽  
O2 Uptake ◽  
Energy Demands ◽  
Interspecific Allometry ◽  
Tropical Freshwater

Abstract. Physiological aspects like heat balance, gas exchange, osmoregulation, and digestion of the early Permian aquatic temnospondyl Archegosaurus decheni, which lived in a tropical freshwater lake, are assessed based on osteological correlates of physiologically relevant soft-tissue organs and by physiological estimations analogous to air-breathing fishes. Body mass (M) of an adult Archegosaurus with an overall body length of more than 1 m is estimated as 7 kg using graphic double integration. Standard metabolic rate (SMR) at 20 °C (12 kJ h−1) and active metabolic rate (AMR) at 25 °C (47 kJ h−1) were estimated according to the interspecific allometry of metabolic rate (measured as oxygen consumption) of all fish (VO2 = 4. 8 M0. 88) and form the basis for most of the subsequent estimations. Archegosaurus is interpreted as a facultative air breather that got O2 from the internal gills at rest in well-aerated water but relied on its lungs for O2 uptake in times of activity and hypoxia. The bulk of CO2 was always eliminated via the gills. Our estimations suggest that if Archegosaurus did not have gills and released 100 % CO2 from its lungs, it would have to breathe much more frequently to release enough CO2 relative to the lung ventilation required for just O2 uptake. Estimations of absorption and assimilation in the digestive tract of Archegosaurus suggest that an adult had to eat about six middle-sized specimens of the acanthodian fish Acanthodes (ca. 8 cm body length) per day to meet its energy demands. Archegosaurus is regarded as an ammonotelic animal that excreted ammonia (NH3) directly to the water through the gills and the skin, and these diffusional routes dominated nitrogen excretion by the kidneys as urine. Osmotic influx of water through the gills had to be compensated for by production of dilute, hypoosmotic urine by the kidneys. Whereas Archegosaurus has long been regarded as a salamander-like animal, there is evidence that its physiology was more fish- than tetrapod-like in many respects.

Notes on Allometry and Prediction of Body Mass and Age of Giraffes

2021 ◽  
pp. 76-84
Author(s):  
Graham Mitchell
Keyword(s):  
Body Mass ◽  
Great Accuracy ◽  
Rate Of Change ◽  
Biological Structures ◽  
Ontogenetic Allometry ◽  
Interspecific Allometry ◽  
Physiological And Biochemical

Quantification of how biological structures change during growth is essential for understanding how giraffes work. Allometry is the best arithmetical tool for analyzing changes that occur during growth. It measures how well the rate of change in one structure is associated with the rate of change in another in the species of interest. If the association is close, then allometry can be used, as in this chapter, to predict the age of a giraffe (from, say, its height) or its body mass (from its length and girth), with great accuracy. The best predictions are made if the data used to make predictions are derived from the particular species, and this type is referred to as ontogenetic allometry. A second type—interspecific allometry—uses data collected from other species to make predictions about the species of interest (like giraffes). Predictions using this second method are less accurate but are useful for establishing anatomical, physiological, and biochemical differences between the species of interest and all other comparable species.

scholarly journals The many faces of synapsid cranial allometry

Paleobiology ◽  
2019 ◽  
Vol 45 (4) ◽  
pp. 531-545
Author(s):  
Isaac W. Krone ◽  
Christian F. Kammerer ◽  
Kenneth D. Angielczyk
Keyword(s):  
Interspecific Variation ◽  
Geometric Morphometric ◽  
Facial Region ◽  
Ontogenetic Trajectory ◽  
The Face ◽  
The Many ◽  
Interspecific Allometry ◽  
Cranial Shape

AbstractPrevious studies of cranial shape have established a consistent interspecific allometric pattern relating the relative lengths of the face and braincase regions of the skull within multiple families of mammals. In this interspecific allometry, the facial region of the skull is proportionally longer than the braincase in larger species. The regularity and broad taxonomic occurrence of this allometric pattern suggests that it may have an origin near the base of crown Mammalia, or even deeper in the synapsid or amniote forerunners of mammals. To investigate the possible origins of this allometric pattern, we used geometric morphometric techniques to analyze cranial shape in 194 species of nonmammalian synapsids, which constitute a set of successive outgroups to Mammalia. We recovered a much greater diversity of allometric patterns within nonmammalian synapsids than has been observed in mammals, including several instances similar to the mammalian pattern. However, we found no evidence of the mammalian pattern within Therocephalia and nonmammalian Cynodontia, the synapsids most closely related to mammals. This suggests that the mammalian allometric pattern arose somewhere within Mammaliaformes, rather than within nonmammalian synapsids. Further investigation using an ontogenetic series of the anomodont Diictodon feliceps shows that the pattern of interspecific allometry within anomodonts parallels the ontogenetic trajectory of Diictodon. This indicates that in at least some synapsids, allometric patterns associated with ontogeny may provide a “path of least resistance” for interspecific variation, a mechanism that we suggest produces the interspecific allometric pattern observed in mammals.

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