Growing with dinosaurs: a review of dinosaur reproduction and ontogeny

Biology Letters, Journal Year: 2025, Volume and Issue: 21(1)

Published: Jan. 1, 2025

Since the start of twenty-first century, there has been a notable increase in annual publications focusing on dinosaur reproduction and ontogeny with researchers using these data to address range macroevolutionary questions about dinosaurs. Ontogeny, which is closely tied osteological morphological variation, impacts several key research areas, such as taxonomic diversity, population dynamics, palaeoecology, macroevolution, well physiological reproductive factors driving ecological success. While broad studies have significantly advanced our understanding evolution, they also revealed important challenges areas needing further investigation. In this review, we aim outline some major linked ontogeny, namely biology, osteohistological growth strategies, variation link between macroevolution. We offer recommendations for best practices promising future directions. These include increasing sample sizes through fieldwork exhaustive use pre-existing fossil collections, micro-computed tomography (μCT) scanning methods dataset non-destructive manner, methodical collection reposition μCT scan data, assessing ontogenetic maturity, establishing consistency terminology building comprehensive extant comparative datasets.

Language: Английский

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Structural Insights into Ratite Birds and Crocodile Eggshells for Advanced Biomaterials Design

ACS Omega, Journal Year: 2025, Volume and Issue: 10(5), P. 5064 - 5079

Published: Jan. 31, 2025

Detailed analysis of particle size, morphology, elemental composition, crystalline structure, and thermal degradation behavior reveals significant differences between ratite crocodile eggshells, showing their unique environmental adaptations biological functions. Ratite characterized by smaller sizes, present lower are more suitable for applications requiring flexibility resilience. In contrast, crocodilian eggshells have extensive denser particles, giving them a uniform structure therefore contributing to higher stability mechanical strength. The variation in activation energy profiles different parts the indicates complexity processes. this regard, ostrich eggshell presents complicated, multistage patterns, may be layered applications. emu suggests its utility systems where consistent performance is essential. Similarly, stable predictable river swamp make ideal candidates environments high durability resistance cycling. This research highlights natural design provides valuable guidance development biomimetic materials. By mimicking structural properties these it would useful create thermally materials wide range industrial biomedical

Language: Английский

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Tooth replacement in the early-diverging neornithischian Jeholosaurus shangyuanensis and implications for dental evolution and herbivorous adaptation in Ornithischia

BMC Ecology and Evolution, Journal Year: 2024, Volume and Issue: 24(1)

Published: April 16, 2024

Abstract Background Tooth replacement patterns of early-diverging ornithischians, which are important for understanding the evolution highly specialized dental systems in hadrosaurid and ceratopsid dinosaurs, poorly known. The neornithischian Jeholosaurus , a small, bipedal herbivorous dinosaur from Early Cretaceous Jehol Biota, is an taxon ornithischian evolution, but its morphology was only briefly described previously tooth Results CT scanning six specimens representing different ontogenetic stages reveals significant new information regarding system including one or two teeth nearly all alveoli, relatively complete resorption, increase numbers alveoli during ontogeny. Reconstructions Zahnreihen indicate that pattern maxillary dentition similar to dentary with cyclical difference. rate probably 46 days, faster than most other ornithischians. During ontogeny premaxillary slows 25 days 33 daily dentine formation. Conclusions exhibits decreasing trend ontogeny, as Alligator . In phylogenetic context, fast multi-generation have evolved at least twice independently Ornithopoda, our analyses suggest members major clades exhibit adaption herbivory.

Language: Английский

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The diverse terminology of reptile eggshell microstructure and its effect on phylogenetic comparative analyses

Journal of Anatomy, Journal Year: 2022, Volume and Issue: 241(3), P. 641 - 666

Published: June 27, 2022

Abstract Reptile eggshell ensures water and gas exchange during incubation plays a key role in reproductive success. The diversity of reptilian life history strategies has led to many clade‐specific structural adaptations their eggshell, which have been studied extant taxa (i.e. birds, crocodilians, turtles, lepidosaurs). Most studies on non‐avian eggshells were performed over 30 years ago categorized reptile into two main types: “hard” “soft” – sometimes with third intermediate category, “semi‐rigid.” In recent years, however, debate the evolution structure major clades revealed how definitions hard soft influence inferred deep‐time evolutionary patterns. Here, we review fossil focus clades, criteria that used define hard, soft, semi‐rigid eggshells. We show all scoring approaches retain these categories discretize continuous quantitative traits (e.g. thickness) do not consider independent variation other functionally important microstructural degree calcification, shell unit inner structure). demonstrate effect three published discretizing type semi‐rigid, ancestral state reconstructions using 200+ species representing extinct clades. These result different states for including Archosauria Dinosauria, despite difference only 1–4% sample. Proposed scenarios are highly conditioned by sampling, tree calibration, lack congruence between type. conclude traditional “soft/hard/semi‐rigid” classification should be abandoned provide guidelines future descriptions focusing specific relevant characteristics structures units, pores, membrane elements), analyses phylogenetic context, sampling previously undescribed taxa, eggs.

Language: Английский

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Exceptional Early Jurassic fossils with leathery eggs shed light on dinosaur reproductive biology

National Science Review, Journal Year: 2023, Volume and Issue: 11(6)

Published: Oct. 9, 2023

ABSTRACT Our understanding of pre-Cretaceous dinosaur reproduction is hindered by a scarcity evidence within fossil records. Here we report three adult skeletons and five clutches embryo-containing eggs new sauropodomorph from the Lower Jurassic southwestern China, displaying several significant reproductive features that are either unknown or unlike other early-diverging sauropodomorphs, such as relatively large with thick calcareous shell formed prominent mammillary cones, synchronous hatching transitional prehatching posture between crocodilians living birds. Most significantly, these Early fossils provide strong for earliest known leathery eggs. comprehensive quantitative analyses demonstrate first were probably leathery, elliptical small, but long eggshell units, along line to birds, most change in reptilian egg morphology occurred early theropod evolution rather than near origin Aves.

Language: Английский

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A Comparative Study on the Microstructures, Mineral Content, and Mechanical Properties of Non-Avian Reptilian Eggshells

Biology, Journal Year: 2023, Volume and Issue: 12(5), P. 688 - 688

Published: May 7, 2023

We analyze 214 freshly laid eggs belonging to 16 species across three orders of Class Reptilia. Using mechanical compression tests, we measure each egg's absolute stiffness (K, unit: N m-1) and relative (C number). The effective Young's modulus, E, was obtained by combining experimental numerical methods. mineral (CaCO3) content measured acid-base titration, the microstructures scanning electron microscopy (SEM), crystallography backscatter diffraction (EBSD). find that C number reptilian is, on average, higher than bird eggs, indicating are stiffer with respect egg mass birds. However, moduli eggshells (32.85 ± 3.48 GPa) similar those avian (32.07 5.95 GPa), even though have different crystal forms, microstructures, crystallography. Titration measurement shows highly mineralized (>89% for nine Testudines 96% Caiman crocodilus). Comparing aragonite calcite crystals, shells, including Kwangsi gecko (inner part) spectacled caiman (outer part), generally larger grains ones. grain size is not correlated modulus. Also, as number, shells are, ones (except gecko), primarily due their thicker shells.

Language: Английский

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Multiscale Mineralization in the Leopard Gecko Eggshell

Advanced Functional Materials, Journal Year: 2024, Volume and Issue: 34(24)

Published: Feb. 23, 2024

Abstract Reptilian (non‐avian) eggshell biomineralization is markedly different from avian eggshells. Despite discontinuous/variable mineralization, the reptilian (like in birds) responsible for protective and developmental functions of egg as part a highly successful reproduction strategy. Using multiscale imaging characterization methods including X‐ray electron microscopy/tomography, 3D overview ultrastructure gekkotan Eublepharis macularius – common leopard gecko provided. Eggshell mineral shown to be sensitive aqueous preparations, where cryogenic are essential accurate organic preservation. Interwoven with underlying fibers involved formation complex hierarchical order eggshell, nucleation growth mineral. The calcitic phase takes on three microstructural motifs at shell surface: nodular scutes (≈40 µm), intermittent blunt or star‐shaped rosettes (≈1 mm), smaller corollas (≈10 µm). Individual have two structures nanospheres (≈500 nm) nanodomains nm). Diverse variable features eggshells likely reflect importance differences ecology physiology formation, survival, mechanics, related hydration sensitivity, structural organic‐inorganic interactions, polymorphism.

Language: Английский

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Hydric environment and chemical composition shape non-avian reptile eggshell absorption

Integrative and Comparative Biology, Journal Year: 2024, Volume and Issue: unknown

Published: May 16, 2024

The amniotic egg fulfils a critical role in reproduction by serving as an interface between the external environment and embryo. Because non-avian reptiles are rarely incubated, they must be heated by, absorb water from, oviposition site for developing mechanisms which sufficient, but not excess, how these vary with local habitat is largely unknown, despite its significance to their evolution. Here, we first performed histology, Fourier-transform infrared spectroscopy dynamic vapor sorption experiments elucidate of eggshell absorption 56 reptile species. Then, used phylogenetic comparative analysis test hypothesis that absorptive capacity eggshells increases aridity environment. We found presence superficial mucopolysaccharide layer decreases increased calcium content. eggs from arid environments have highly absorbent eggshells, only species weakly calcified shells. Our results suggest over evolutionary time tuned environmental moisture level. Since often sustain conflicting constraints, may serve inspirations new biomimetic materials, such filtering membranes or humidity sensors.

Language: Английский

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Breaking through the eggshell: embryonic development of the premaxillary dentition in Lacerta agilis (Squamata: Unidentata) with special emphasis on the egg tooth

Zoological Journal of the Linnean Society, Journal Year: 2024, Volume and Issue: 201(4)

Published: Aug. 1, 2024

Abstract The egg tooth of squamates is a true that allows them to break, tear, or cut the eggshell during hatching. In this clade there are some uncertainties concerning implantation geometry, number germs, and their fates embryonic development. Here, we used X-ray microtomography light microscopy, focusing on remaining premaxillary teeth sand lizard (Lacerta agilis, Squamata: Unidentata). developing species passes through all classic stages We did not find any evidence large size related merging two which has recently been suggested occur in snakes. Instead, feature can be attributed delayed formation neighbouring regular teeth. This might provide more resources tooth. At last developmental stage, large, midline structure, bent forward as most oviparous Unidentata. It characterized by pleurodont implantation, its base attached pleura peculiar ridge alveolar bone. attachment tissue contains periodontal ligament-like tissue, acellular cementum-like

Language: Английский

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Turtle eggs from the Lower Cretaceous Hasandong Formation (South Korea) with relict aragonite under significant thermal maturity

Journal of Vertebrate Paleontology, Journal Year: 2022, Volume and Issue: 42(4)

Published: Oct. 28, 2022

Unlike the eggshells of other amniotes, turtle are composed aragonite, which is a metastable mineral. Turtle in fossil record therefore usually transformed to calcite. Geothermal heat also negatively affects preservation and aragonite under geothermal settings not expected. Here we report new eggs from Lower Cretaceous (Aptian–Albian) Hasandong Formation South Korea, describing morphological features eggshells. The belong an oogenus Testudoolithus with smallest recorded egg size. As one oldest this material fills paleobiogeographic gap East Asia, has limited records for non-dinosaurian reptiles. More importantly, presence relict was cross-validated by electron backscatter diffraction Raman spectroscopy. spectra thermally altered organic matter inside indicated that experienced maximum temperature almost 260°C during their taphonomic history. This implies can be preserved even hostile thermal conditions earlier reports 'calcite-only' may preserve undetected only detectable via careful investigation using advanced microscopic techniques. combined use mineralogical spectroscopic approaches adopted study useful invertebrate paleontology archeology further understand relationship between paleotemperature materials experienced.

Language: Английский

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