Osteohistology of the non-mammaliaform traversodontids<i>Protuberum cabralense</i>and<i>Exaeretodon riograndensis</i>from southern Brazil

Veiga, Fábio Hiratsuka; Botha‐Brink, Jennifer; Soares, Marina Bento

doi:10.1080/08912963.2018.1441292

Cited by 7 publications

(18 citation statements)

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“…It is clear from the highly vascularized, rapidly deposited bone tissues that Prozostrodon grew quickly during the favorable growing season. The expansive width of the slow growing parallel-fibered zone is noteworthy, however, as this differs from the gomphodonts that have been studied to date (i.e., Diademodon , Trirachodon , Langbergia , Andescynodon , Traversodon , Gomphodontosuchus , Protuberum , Scalenodontoides , Exaeretodon ; Botha & Chinsamy, 2000 ; Botha & Chinsamy, 2004 ; Chinsamy & Abdala, 2008 ; Botha-Brink, Abdala & Chinsamy, 2012 ; Veiga, Botha-Brink & Soares, 2018 ), all of which express LAGs or narrow annuli of parallel-fibered or lamellar bone. The broadness of this slow growing zone indicates that either the animal was able to continue growing through much of the cold or dry season, only ceasing when the LAG was deposited, or that it experienced a particularly long and harsh unfavorable growing season and thus, grew slowly for longer under these conditions.…”

Section: Discussionmentioning

confidence: 96%

“…Life history data, such as growth patterns and growth rates and how these change through ontogeny, can be obtained from extinct vertebrates by studying their bone microstructure or osteohistology. Given the importance of non-mammaliaform cynodonts in understanding the origin and evolution of mammalian growth patterns, numerous osteohistological studies have been conducted, but these have mostly focused on basal taxa and the more derived Cynognathia (e.g., De Ricqlès, 1969 ; Botha & Chinsamy, 2000 ; Botha & Chinsamy, 2004 ; Botha & Chinsamy, 2005 ; Ray, Botha & Chinsamy, 2004 ; Chinsamy & Abdala, 2008 ; Botha-Brink, Abdala & Chinsamy, 2012 ; Veiga, Botha-Brink & Soares, 2018 ; Butler, Abdala & Botha-Brink, 2018 ). These studies indicate that fibrolamellar bone (indicative of rapid bone deposition rates) is the dominant bone tissue type, at least during early to middle ontogeny.…”

Section: Introductionmentioning

confidence: 99%

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Osteohistology of Late Triassic prozostrodontian cynodonts from Brazil

Botha‐Brink

Soares

Martinelli

2018

PeerJ

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The Prozostrodontia includes a group of Late Triassic-Early Cretaceous eucynodonts plus the clade Mammaliaformes, in which Mammalia is nested. Analysing their growth patterns is thus important for understanding the evolution of mammalian life histories. Obtaining material for osteohistological analysis is difficult due to the rare and delicate nature of most of the prozostrodontian taxa, much of which comprises mostly of crania or sometimes even only teeth. Here we present a rare opportunity to observe the osteohistology of several postcranial elements of the basal prozostrodontid Prozostrodon brasiliensis, the tritheledontid Irajatherium hernandezi, and the brasilodontids Brasilodon quadrangularis and Brasilitherium riograndensis from the Late Triassic of Brazil (Santa Maria Supersequence). Prozostrodon and Irajatherium reveal similar growth patterns of rapid early growth with annual interruptions later in ontogeny. These interruptions are associated with wide zones of slow growing bone tissue. Brasilodon and Brasilitherium exhibit a mixture of woven-fibered bone tissue and slower growing parallel-fibered and lamellar bone. The slower growing bone tissues are present even during early ontogeny. The relatively slower growth in Brasilodon and Brasilitherium may be related to their small body size compared to Prozostrodon and Irajatherium. These brasilodontids also exhibit osteohistological similarities with the Late Triassic/Early Jurassic mammaliaform Morganucodon and the Late Cretaceous multituberculate mammals Kryptobaatar and Nemegtbaatar. This may be due to similar small body sizes, but may also reflect their close phylogenetic affinities as Brasilodon and Brasilitherium are the closest relatives to Mammaliaformes. However, when compared with similar-sized extant placental mammals, they may have grown more slowly to adult size as their osteohistology shows it took more than one year for growth to attenuate. Thus, although they exhibit rapid juvenile growth, the small derived, brasilodontid prozostrodontians still exhibit an extended growth period compared to similar-sized extant mammals.

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Section: Discussionmentioning

confidence: 96%

Section: Introductionmentioning

confidence: 99%

Osteohistology of Late Triassic prozostrodontian cynodonts from Brazil

Botha‐Brink

Soares

Martinelli

2018

PeerJ

Self Cite

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“…The expansive width of the slow growing parallel-fibered zone is noteworthy, however, as this differs from the gomphodonts that have been studied to date (i.e. Diademodon, Trirachodon, Langbergia, Andescynodon, Traversodon, Gomphodontosuchus, Protuberum, Scalenodontoides, Exaeretodon;Chinsamy, 2000, 2004;Chinsamy and Abdala, 2008;Botha-Brink, Abdala and Chinsamy, 2012;Veiga, Botha-Brink and Soares, 2018), all of which express LAGs or narrow annuli of parallel-fibered or lamellar bone. The broadness of this slow growing zone indicates that either the animal was able to continue growing through much of the cold or dry season, only ceasing when the LAG was deposited, or that it experienced a particularly long and harsh unfavorable growing season and thus, grew slowly for longer under these conditions.…”

Section: Manuscript To Be Reviewedmentioning

confidence: 92%

Peer Review #2 of "Osteohistology of Late Triassic prozostrodontian cynodonts from Brazil (v0.1)"

Hoffmann¹

2018

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The Prozostrodontia includes a group of Late Triassic-Early Cretaceous eucynodonts plus the clade Mammaliaformes, in which Mammalia is nested. Analysing their growth patterns is thus important for understanding the evolution of mammalian life histories. Obtaining material for osteohistological analysis is difficult due to the rare and delicate nature of most of the prozostrodontian taxa much of which comprises mostly crania or sometimes even only teeth. Here we present a rare opportunity to observe the osteohistology of several postcranial elements of the basal prozostrodontid Prozostrodon brasiliensis, the tritheledontid Irajatherium hernandezi, and the brasilodontids Brasilodon quadrangularis and Brasilitherium riograndensis from the Late Triassic of Brazil (Santa Maria Supersequence). Prozostrodon and Irajatherium reveal similar growth patterns of rapid early growth with annual interruptions later in ontogeny. These interruptions are associated with wide zones of slow growing bone tissue. Brasilodon and Brasilitherium exhibit a mixture of woven-fibered bone tissue and slower growing parallel-fibered and lamellar bone. The slower growing bone tissues are present even during early ontogeny. The relatively slower growth in Brasilodon and Brasilitherium may be related to their small body size compared to Prozostrodon and Irajatherium. These brasilodontids also exhibit osteohistological similarities with the Late Triassic/Early Jurassic mammaliaform Morganucodon and the Late Cretaceous multituberculate mammals Kryptobaatar and Nemegtbaatar. This may be due to similar small body sizes, but may also reflect their close phylogenetic affinities as Brasilodon and Brasilitherium are the closest relatives to the Mammaliaformes. However, when compared with similar-sized extant placental mammals, they may have grown more slowly to adult size as their osteohistology shows it took more than one year for growth to attenuate. Thus, although they exhibit rapid juvenile growth, the small derived, brasilodontid prozostrodontians still exhibit an extended growth period compared to similar-sized extant mammals.

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“…To date, 25 species of non-mammalian cynodont have been histologically sampled (Fig. 1; Table 1; Botha-Brink et al, 2012, 2018; Botha & Chinsamy, 2000, 2004, 2005; Botha & Huttenlocker, 2021; Butler et al, 2019; Chinsamy & Abdala, 2008; Chinsamy & Hurum, 2006; de Ricqlès, 1969; Garcia Marsà et al, 2022; Ray et al, 2004; Veiga et al, 2018; Wynd et al, 2018). Previous studies have focused on early diverging members (e.g., Procynosuchus , Thrinaxodon , Galesaurus ) to provide insights into the growth rates and developmental patterns that might have contributed to the survival of the cynodont lineage through the end-Permian mass extinction (Botha & Chinsamy, 2005; Butler et al, 2019; de Ricqlès, 1969).…”

Section: Introductionmentioning

confidence: 99%

Rare osteohistological evidence of skeletal maturity in the early diverging traversodontid Scalenodon angustifrons , with comments on histological sampling coverage in Cynodontia

Kulik

2023

Journal of Vertebrate Paleontology

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To date, 25 species of non-mammalian cynodonts have been histologically sampled, but few record a definitive and well-developed external fundamental system (EFS) indicative of skeletal maturity. Here, I report an EFS in the femoral histology of Scalenodon angustifrons and discuss the factors that could explain why skeletally mature tissue is rarely documented in cynodont osteohistology. My sample includes two equivalently sized individuals that document marked histological variation, as only one shows evidence of slowing growth rate and an EFS. Variation in the bone histology between femora of the same size suggests that attainment of skeletal maturity does not follow a discrete developmental pattern for S. angustifrons, a pattern that is also seen in the bone histology of other traversodontids and some nongomphodontian cynodonts. From these results, a flexible growth strategy is inferred for S. angustifrons. To contextualize the validity of this pattern among other cynodont species, I summarize the sampling coverage of cynodonts that have been thin-sectioned and report limited coverage across size classes/ inferred development stages. This is often a result of sampling one isolated element that is not standardized to one skeletal element, which contributes to a poorly constrained comparative sample (in terms of size coverage, spatial and temporal resolution, and taxonomic coverage). Despite this, many cynodont species show shifts towards slow growth, but very few instances of unequivocal evidence of skeletal maturity. This result underscores the need for standardized iterative histological sampling to assess longevity, life history, and developmental patterns of non-mammalian cynodonts more accurately.

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Osteohistology of the non-mammaliaform traversodontidsProtuberum cabralenseandExaeretodon riograndensisfrom southern Brazil

Cited by 7 publications

References 37 publications

Osteohistology of Late Triassic prozostrodontian cynodonts from Brazil

Osteohistology of Late Triassic prozostrodontian cynodonts from Brazil

Peer Review #2 of "Osteohistology of Late Triassic prozostrodontian cynodonts from Brazil (v0.1)"

Rare osteohistological evidence of skeletal maturity in the early diverging traversodontid Scalenodon angustifrons , with comments on histological sampling coverage in Cynodontia

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