Growth and miniaturization among alvarezsauroid dinosaurs
Open accessAbstract
Sustained miniaturization, here defined as a drop in body size of at least two orders of magnitude from ancestors to descendants, is a widespread and important phenomenon in animals,1-3 but among dinosaurs, miniaturization occurred only rarely, once in the lineage leading to birds and once in the Alvarezsauroidea,1,3-5 one of the most bizarre theropod groups.1,5-7 Miniaturization and powered flight are intimately linked in avialan theropods,3,5,6,8-11 but the causes and patterns of body size reduction are less clear in the non-volant Alvarezsauroidea.1,5,6,12,13 Here, we present results from analyses on a comprehensive dataset, which not only includes new data from early-branching alvarezsauroids but also considers the ontogenetic effect based on histological data. Our analyses show that alvarezsauroid body mass underwent rapid miniaturization from around 110 to 85 mya and that there was a phylogenetic radiation of small-sized alvarezsauroids in the Late Cretaceous. Our analyses also indicate that growth strategies were highly variable among alvarezsauroids, with significant differences among extremely small taxa. The suggested alvarezsauroid miniaturization and associated phylogenetic radiation are coincident with the emergence of ants and termites, and combining previous functional morphological data, our study suggests that alvarezsauroid miniaturization might have been driven by ecological changes during the Cretaceous Terrestrial Revolution, more specifically by a shift to the myrmecophagous ecological niche.
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The teeth of Archaeopteryx lack serrations, as in anchiornithines, some troodontids (e.g., Byronosaurus) and other Mesozoic birds.
“As in anchiornithines, some troodontids (e.g., Byronosaurus ) and other Mesozoic birds, the teeth lack serrations [81-83] (Fig.3).”
From The ecology of Archaeopteryx (2026) · cites this paper as [81]
The number of teeth is reduced from 14 maxillary and 16 dentary teeth in Anchiornis to 8-10 maxillary and 11-13 dentary teeth in Archaeopteryx.
“The number of teeth is reduced from 14 maxillary and 16 dentary teeth in Anchiornis , a taxon documented to be at least partially vertivorous [84], to 8-10 maxillary and 11-13 dentary teeth in Archaeopteryx [13, 81].”
From The ecology of Archaeopteryx (2026) · cites this paper as [81]
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“The notion of adaptive radiation in the Late Cretaceous (e.g. Meso et al., 2024; Qin et al., 2021) is supported by the significant rise in morphological diversity during this time, which records the WMPD peak value (see Supplementary Information 11: Table S1).”
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- Authors
- Qin, Z., Zhao, Q., Choiniere, J. N., Clark, J. M., Benton, M. J., & Xu, X.
- Affiliations
- University of Bristol (GB)
- Chinese Academy of Sciences (CN)
- University of the Witwatersrand (ZA)
- George Washington University (US)
- Corresponding author
- Xu, Xing
- Venue
- Current Biology
- Publisher
- Elsevier BV
- Published
- 2021-08
- Volume
- 31
- Issue
- 16
- Pages
- 3687-3693.e5
- ISSN
- 0960-9822 (ISSN-L)
- PMC
- PMC8409485
- OpenAlex
- W3178159540
- Cited by
- 25
- References
- 70
- Citations by year
- 2026: 6 · 2025: 5 · 2024: 3 · 2023: 8 · 2022: 2 · 2021: 1
- FWCI
- 2.63
- Type
- journal article
- Language
- en
- Update notices
- erratum (2021-08-23)
- Open access
- bronze
- doi.org
- Licence
- www.elsevier.com/tdm/userlicense/1.0/ (tdm)
- www.elsevier.com/legal/tdmrep-license (tdm)
- www.elsevier.com/open-access/userlicense/1.0/ (vor, 387 d)
- doi.org/10.15223/policy-017 (stm-asf)
- doi.org/10.15223/policy-037 (stm-asf)
- doi.org/10.15223/policy-012 (stm-asf)
- doi.org/10.15223/policy-029 (stm-asf)
- doi.org/10.15223/policy-004 (stm-asf)
- Locations
- Current Biology (publishedVersion)
- PubMed Central (publishedVersion)
- PubMed (publishedVersion)
- Explore Bristol Research (submittedVersion)
- Funders
- European Research Council
- Royal Society (NA160290, 42072008)
- National Research Foundation
- National Natural Science Foundation of China (41688103, 41120124002)
- National Science Foundation (EAR 0310217)
- National Research Foundation of Korea (AOP 98800, IRG 95449, AOP 118794)
- Topics
- Physical Sciences › Earth and Planetary Sciences › Paleontology › Paleontology and Evolutionary Biology
- Physical Sciences › Earth and Planetary Sciences › Paleontology › Evolution and Paleontology Studies
- Life Sciences › Agricultural and Biological Sciences › Ecology, Evolution, Behavior and Systematics › Fossil Insects in Amber
- Keywords
- body size reduction, ontogeny, histology, Late Cretaceous, myrmecophagy, ecological niche shift, body mass
- MeSH terms
- Animals, Biological Evolution, Fossils, Phylogeny, Dinosaurs
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