Fossoriality and evolutionary development in two Cretaceous mammaliamorphs

Acoustic communication has played a key role in the evolution of a wide variety of vertebrates and insects. However, the reconstruction of ancient acoustic signals is challenging due to the extreme rarity of fossilized organs. Here, we report the earliest tympanal ears and sound-producing system (stridulatory apparatus) found in exceptionally preserved Mesozoic katydids. We present a database of the stridulatory apparatus and wing morphology of Mesozoic katydids and further calculate their probable singing frequencies and analyze the evolution of their acoustic communication. Our suite of analyses demonstrates that katydids evolved complex acoustic communication including mating signals, intermale communication, and directional hearing, at least by the Middle Jurassic. Additionally, katydids evolved a high diversity of singing frequencies including high-frequency musical calls, accompanied by acoustic niche partitioning at least by the Late Triassic, suggesting that acoustic communication might have been an important driver in the early radiation of these insects. The Early—Middle Jurassic katydid transition from Haglidae- to Prophalangopsidae-dominated faunas coincided with the diversification of derived mammalian clades and improvement of hearing in early mammals, supporting the hypothesis of the acoustic coevolution of mammals and katydids. Our findings not only highlight the ecological significance of insects in the Mesozoic soundscape but also contribute to our understanding of how acoustic communication has influenced animal evolution.

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“…( B ) Simplified phylogeny of mammaliaforms based on ref. 33 . Black thick lines indicate the known extent of the fossil record.…”

Section: Resultsmentioning

confidence: 99%

High acoustic diversity and behavioral complexity of katydids in the Mesozoic soundscape

Wang

Wappler

et al. 2022

Proc. Natl. Acad. Sci. U.S.A.

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“…Recent studies have examined axial regionalization near the origin of crown mammals and in several extant clades 28,29,[53][54][55][56][57][58][59]66 . Furthermore, inferred ancestral conditions for vertebral counts have been mapped onto phylogenies to reconstruct major shifts in homoeotic domains 48,49,52,53,56,67 .…”

Section: Articlementioning

confidence: 99%

Divergent vertebral formulae shape the evolution of axial complexity in mammals

Brinkworth

Green

et al. 2023

Nat Ecol Evol

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Complexity, defined as the number of parts and their degree of differentiation, is a poorly explored aspect of macroevolutionary dynamics. The maximum anatomical complexity of organisms has undoubtedly increased through evolutionary time. However, it is unclear whether this increase is a purely diffusive process or whether it is at least partly driven, occurring in parallel in most or many lineages and with increases in the minima as well as the means. Highly differentiated and serially repeated structures, such as vertebrae, are useful systems with which to investigate these patterns. We focus on the serial differentiation of the vertebral column in 1,136 extant mammal species, using two indices that quantify complexity as the numerical richness and proportional distribution of vertebrae across presacral regions and a third expressing the ratio between thoracic and lumbar vertebrae. We address three questions. First, we ask whether the distribution of complexity values in major mammal groups is similar or whether clades have specific signatures associated with their ecology. Second, we ask whether changes in complexity throughout the phylogeny are biased towards increases and whether there is evidence of driven trends. Third, we ask whether evolutionary shifts in complexity depart from a uniform Brownian motion model. Vertebral counts, but not complexity indices, differ significantly between major groups and exhibit greater within-group variation than recognized hitherto. We find strong evidence of a trend towards increasing complexity, where higher values propagate further increases in descendant lineages. Several increases are inferred to have coincided with major ecological or environmental shifts. We find support for multiple-rate models of evolution for all complexity metrics, suggesting that increases in complexity occurred in stepwise shifts, with evidence for widespread episodes of recent rapid divergence. Different subclades evolve more complex vertebral columns in different configurations and probably under different selective pressures and constraints, with widespread convergence on the same formulae. Further work should therefore focus on the ecological relevance of differences in complexity and a more detailed understanding of historical patterns.

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“…4 | Phylogeny of Mesozoic mammaliaforms. The topology is based on the strict consensus of parsimony analysis using a modified morphological character matrix from previous studies 9,20,72,73 . Eutherians discovered in Early Cretaceous Jehol Biota are on the upper part of the tree with their names highlighted in red.…”

Section: Middle Ear Morphologymentioning

confidence: 99%

“…The simplified topology is modified from the strict consensus of the parsimony analysis (Fig. 4), using a morphological character matrix modified from several sources 9,20,72,73 . The pattern of ear evolution highlights three morphotypes of the middle ear (PAME, MAME, and DME) and three morphotypes of the incudomallear joint (QJ, OJ, and SSJ), coupled with the innovation of tribosphenic teeth in non-allotherian clades.…”

Section: Evolutionary Innovation Of Incudomallear Joint In Deep Timementioning

confidence: 99%

Middle ear innovation in Early Cretaceous eutherian mammals

Wang,

Wang

2023

Nat Commun

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The middle ear ossicles in modern mammals are repurposed from postdentary bones in non-mammalian cynodonts. Recent discoveries by palaeontological and embryonic studies have developed different models for the middle ear evolution in mammaliaforms. However, little is known about the evolutionary scenario of the middle ear in early therians. Here we report a detached middle ear preserved in a new eutherian mammal from the Early Cretaceous Jehol Biota. The well-preserved articulation of the malleus and incus suggest that the saddle-shaped incudomallear joint is a major apomorphy of Early Cretaceous eutherians. By contrast to the distinct saddle-like incudomallear articulation in therians, differences between the overlapping versus the half-overlapping incudomallear joints in monotremes and stem mammals would be relatively minor. The middle ear belongs to the microtype by definition, indicating its adaptation to high-frequency hearing. Current evidence indicates that significant evolutionary innovations of the middle ear in modern therians evolved in Early Cretaceous.

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Fossoriality and evolutionary development in two Cretaceous mammaliamorphs

Cited by 23 publications

References 66 publications

High acoustic diversity and behavioral complexity of katydids in the Mesozoic soundscape

High acoustic diversity and behavioral complexity of katydids in the Mesozoic soundscape

Divergent vertebral formulae shape the evolution of axial complexity in mammals

Middle ear innovation in Early Cretaceous eutherian mammals

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