Variability of growth pattern observed in Metoposaurus krasiejowensis humeri and its biological meaning

Abstract

Purpose Histological studies on temnospondyl amphibian bones remain rare. A systematic revision of the histology was applied for the purpose of testing the histovariability in the humeri and becoming new information about the growth pattern. Methods The present study includes 12 humeri of Metoposaurus krasiejowensis, which originate from the Late Triassic clay pit near Krasiejów, southwestern Poland. The specimens were scanned with a microCT and the histological thin-sections have been obtained with the standard petrographic method. Results The evaluation of the studied bones shows a uniform growth series resulting in one morphotype. Strikingly, the histological analysis reveals a greater diversity with two different histotypes: Histotype I shows a distinct differentiation between alternating zones and annuli with poor to moderate vascularization and increase of bone remodeling during growth. Histotype II does not show any distinct zones and annuli but is characterized by a high vascularization and fast growth coexisting with an extensive bone remodeling. Conclusions Based on these two different growth patterns, several hypotheses can be established: The specimens do not show any pattern of histological variation; humeri represent a taxonomic diversity; the analyzed Metoposaurus bones stem from two different populations separated by space and; or time or sexual dimorphism.

Merging cranial histology and 3D-computational biomechanics: a review of the feeding ecology of a Late Triassic temnospondyl amphibian

“…To test whether or not FEA models and histological results provided similar predictions of cranial mechanical behaviour under feeding loads, the present paper compares results from both methods for a well-known taxon. The early tetrapod Metoposaurus krasiejowensis ( Sulej, 2002 ) (Metoposauridae, Temnospondyli) from the Upper Triassic of southwest Poland provides an interesting case study in view of the great number of excellently preserved specimens recovered as well as the extensive data set for this taxon ( Sulej, 2002 ; Sulej, 2007 ; Barycka, 2007 ; Konietzko-Meier & Klein, 2013 ; Konietzko-Meier & Sander, 2013 ; Gruntmejer, Konietzko-Meier & Bodzioch, 2016 ; Fortuny, Marcè-Noguè & Konietzko-Meier, 2017 ; Teschner, Sander & Konietzko-Meier, 2017 ).…”

Limb-Bone Development of Seymouriamorphs: Implications for the Evolution of Growth Strategy in Stem Amniotes

“…Previous histological studies on the humerus of temnospondyls (Figure 1) have shown a great diversity of bone patterns with a large range of cortical vascular densities and growth rates (de Ricqlès, 1979Ricqlès, , 1981Steyer et al, 2004;Laurin et al, 2006;Witzmann, 2009;Mukherjee et al, 2010;Sanchez et al, 2010a,b;Konietzko-Meier and Klein, 2013;Konietzko-Meier and Sander, 2013;Sanchez and Schoch, 2013;McHugh, 2014;Canoville and Chinsamy, 2015;Teschner et al, 2018). This histodiversity partly results from a significant size variability and wide range of temnospondyl lifestyles (Schoch, 2009(Schoch, , 2014Sanchez et al, 2010b).…”

Peer Review #1 of "Ornamentation of dermal bones of Metoposaurus krasiejowensis and its ecological implications (v0.1)"

“…The dimorphic character of clavicles described herein and the two growth patterns of dermal and long 362 bones (humeri) (Teschner, Sander & Konietzko-Meier, 2017) suggest that the ontogeny of specimens 363 assigned to Metoposaurus krasiejowensis could have proceeded via a different growth rate and time 364 span of metamorphosis, caused by differing environmental conditions. The similar number of specimens 365 from both populations (Tc1/Tc2 -44%/56% and Ts1/Ts2 -53%/47%) suggests stable populations.…”