Modern birds deeper origin in Mesozoic + Vegavis skull and early bird evolution
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Ben Creisler
Jun 9, 2025, 1:53:20 PMJun 9
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Ben Creisler
New avian papers:
Free pdf:
Shaoyuan Wu, Ziqi Tao, Liang Liu, Charles R Marshall, Scott V Edwards, Zhonghe Zhou & Frank E Rheindt (2025)
New Fossils Imply a Deeper Origin of Modern Birds in the Mesozoic
National Science Review, nwaf238
doi: https://doi.org/10.1093/nsr/nwaf238
https://academic.oup.com/nsr/advance-article/doi/10.1093/nsr/nwaf238/8158921
Macroevolutionary forces, such as rare catastrophes, have repeatedly disrupted and reset the evolutionary trajectories of Earth's major organismal groups. The Cretaceous–Paleogene (K/Pg) extinction event, approximately 66 Mya, resulted in the demise of ∼75% of all species at the time. Yet despite its magnitude, many major organismal lineages successfully passed through this mass extinction. The evolutionary origins of modern birds (crown-group Aves) remain a subject of substantial debate, as they are often thought to have undergone their primary diversification following the K/Pg boundary. In this perspective, we summarize the various approaches that have been applied to understanding the timing of avian diversification. We examined the inferred divergence times derived from modern phylogenomic studies based on datasets comprising 50 to over 300 whole genomes. Additionally, we evaluate the factors contributing to the continued discrepancies in divergence time estimates. Furthermore, we discuss significant new fossil discoveries from the Late Jurassic and Late Cretaceous periods that reshape our understanding of key evolutionary events in early avian diversification. Taken together, the paleontological evidence increasingly supports a Cretaceous origin for many extant bird lineages, with the major burst of ordinal diversification likely occurring prior to the K/Pg boundary—concurrent with the early radiations of flowering plants, pollinating insects, mammals, fishes, and other groups that characterized the Cretaceous Angiosperm Terrestrial Revolution.
Shaoyuan Wu, Ziqi Tao, Liang Liu, Charles R Marshall, Scott V Edwards, Zhonghe Zhou & Frank E Rheindt (2025)
New Fossils Imply a Deeper Origin of Modern Birds in the Mesozoic
National Science Review, nwaf238
doi: https://doi.org/10.1093/nsr/nwaf238
https://academic.oup.com/nsr/advance-article/doi/10.1093/nsr/nwaf238/8158921
Macroevolutionary forces, such as rare catastrophes, have repeatedly disrupted and reset the evolutionary trajectories of Earth's major organismal groups. The Cretaceous–Paleogene (K/Pg) extinction event, approximately 66 Mya, resulted in the demise of ∼75% of all species at the time. Yet despite its magnitude, many major organismal lineages successfully passed through this mass extinction. The evolutionary origins of modern birds (crown-group Aves) remain a subject of substantial debate, as they are often thought to have undergone their primary diversification following the K/Pg boundary. In this perspective, we summarize the various approaches that have been applied to understanding the timing of avian diversification. We examined the inferred divergence times derived from modern phylogenomic studies based on datasets comprising 50 to over 300 whole genomes. Additionally, we evaluate the factors contributing to the continued discrepancies in divergence time estimates. Furthermore, we discuss significant new fossil discoveries from the Late Jurassic and Late Cretaceous periods that reshape our understanding of key evolutionary events in early avian diversification. Taken together, the paleontological evidence increasingly supports a Cretaceous origin for many extant bird lineages, with the major burst of ordinal diversification likely occurring prior to the K/Pg boundary—concurrent with the early radiations of flowering plants, pollinating insects, mammals, fishes, and other groups that characterized the Cretaceous Angiosperm Terrestrial Revolution.
===
Daniel J. Field (2025)
Paleontology: Ducks all the way down?
Current Biology 35(11): R409--R412
doi: https://doi.org/10.1016/j.cub.2025.03.051
https://www.sciencedirect.com/science/article/abs/pii/S0960982225003677
https://www.cell.com/current-biology/abstract/S0960-9822(25)00367-7
A new fossil from the Cretaceous of Antarctica reveals the skull of the enigmatic bird Vegavis. Unraveling the broader implications of this find for our understanding of early bird evolution will inspire further comparative work.
Paleontology: Ducks all the way down?
Current Biology 35(11): R409--R412
doi: https://doi.org/10.1016/j.cub.2025.03.051
https://www.sciencedirect.com/science/article/abs/pii/S0960982225003677
https://www.cell.com/current-biology/abstract/S0960-9822(25)00367-7
A new fossil from the Cretaceous of Antarctica reveals the skull of the enigmatic bird Vegavis. Unraveling the broader implications of this find for our understanding of early bird evolution will inspire further comparative work.
Thomas Yazbek
Jun 16, 2025, 10:06:42 PMJun 16
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Re: Wu et al.
Bit of a necro here, but I remain skeptical of the repeated assertion that there's all this undiscovered neornithine diversity deep into the Cretaceous. Wasn't it Mickey on here who said Baminornis' "pygostyle" was actually a synsacrum? Vegavis and kin only prove that the galloanserans were distinct by the Maastrichtian. It doesn't prove that *any* other modern orders of birds were present, and given that modern therian mammal groups are also basically absent before the Cenozoic, I really don't feel like there's a reason to abandon the idea of an explosive radiation after K-T.
Bit of a necro here, but I remain skeptical of the repeated assertion that there's all this undiscovered neornithine diversity deep into the Cretaceous. Wasn't it Mickey on here who said Baminornis' "pygostyle" was actually a synsacrum? Vegavis and kin only prove that the galloanserans were distinct by the Maastrichtian. It doesn't prove that *any* other modern orders of birds were present, and given that modern therian mammal groups are also basically absent before the Cenozoic, I really don't feel like there's a reason to abandon the idea of an explosive radiation after K-T.
Note that I'm just a layperson, but based on my knowledge of the literature, it doesn't seem like it's possible yet to answer the question of how much crown Aves diversified before K-T. Vegavis + Asteriornis are from the very end of the Maastrichtian, supposedly there are anseriforms in the Campanian, but I am pretty skeptical that crown Aves was present much before that stage. Stem-Neornithes being present before that time would make a lot of sense, however, probably related to the Cretaceous terrestrial revolution.
I'm a bit ignorant of the current state of science on the matter, but to my knowledge, most bird material alleged to belong to modern neoavian orders is found pretty late (in the Campanian-Maastrichtian). There is no trace of the paleognaths. I'm also really ignorant of the biogeographic aspects of this picture, since it seems like most of the material I just mentioned is from a few deposits in North America, Mongolia-Manchuria, and western Europe. If early neoavians were present in a variety of places earlier than the latest Maastrichtian, then presumably at least the basal divisions in that group could have happened before K-T. If somebody could let me know if I'm making sense, or if I missed some recent news supporting the authors' conclusions, or if I didn't interpret the paper correctly, I would appreciate it.
Thomas Yazbeck
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Alberta Claw
Jun 17, 2025, 7:31:17 AMJun 17
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This paper is essentially a summary of Wu et al. (2024) in PNAS (which shares most of the same authors). That study inferred extensive diversification of Neoaves in the Cretaceous, a result that is at odds with nearly all other divergence time estimates for crown-birds in the last decade or so (e.g., Jarvis et al,. 2014; Claramunt and Cracraft, 2015; Prum et al., 2015; Kimball et al., 2019; Kuhl et al., 2021; Brocklehurst and Field, 2024; Stiller et al., 2024).
(Just for clarity's sake: Neornithes is the avian crown group, whereas Neoaves is a [large] subset of Neornithes. We are confident that Neornithes had originated by the end of the Cretaceous as we have fossil evidence for them in the form of Vegavis and Asteriornis, but far less so regarding crown-group Neoaves. The oldest definitive neoavian fossils are from the Paleocene. Purported Mesozoic neoavian fossils reported in older literature are highly fragmentary remains that should be interpreted with caution.)
The paper goes on to discuss new fossil discoveries (the skull of Vegavis, Baminornis, and the U-shaped furcula found at the same locality as the latter) in the context of their findings, but you are right to doubt their relevance to the question of neoavian origins. Vegavis (and Asteriornis) are thought to be members of Galloanserae and are therefore not informative regarding the degree of neoavian diversification in the Cretaceous. Whereas even if one accepts the evidence for a pygostyle in Baminornis (which has been questioned, as you correctly recall), all the Nanyuan fossils show is that avialans possessing a pygostyle (and those with a U-shaped furcula) existed in the Tithonian, not direct evidence for when crown-birds (let alone neoavians) evolved.
Long story short, I would not take this review as representative of current consensus in crown-bird systematics.
Ethan Schoales
Jun 17, 2025, 7:34:40 AMJun 17
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What about Teviornis?
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Alberta Claw
Jun 17, 2025, 7:52:29 AMJun 17
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Teviornis is hypothesized to be a galloanseran (specifically a presbyornithid) and therefore also not relevant to the timing of neoavian origins. I maintain some skepticism of its proposed affinities as it is known only from forelimb bones, which, in addition to being prone to homoplasy among birds in general, are known to be morphologically similar among presbyornithids, some neoavians (e.g., stem-Mirandornithes), and near-crown stem-birds, but I'm not opposed to the possibility that it represents a presbyornithid (or at least total-group anseriform).
e w
Jun 17, 2025, 12:34:51 PMJun 17
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Well there is quite a bunch of neornithean material that does not *seem* to be galloanserine or paleognath, but most discoveries since Hope (2002) are very fragmentary (it's just that thoise few which are not get all the press coverage and most of the research effort).
Of course we still have the 19th-century "transitional shorebird"/"cimolopterygid" material, much understudied by modern standards, which given the last 3 decades' Canadian finds should urgently be revised and compared especially with these; *all* of it. A Mesozoic gruiform-charadriiform split, for example, or Mesozoic distinctness of the phaetontiforms, or even Mesozoic distinctness of Lari and Charadrii within charadriiforms, is entirely possible. Some degree of radiation within Aequornithes (requiring non-Aequornithes Neoaves as a distinct lineage) in the Mesozoic is also suggested by even the earliest Pg stem penguins being surprisingly derived already. And it is probably safe to say that these most likely candidates for a Mesozoic neoavian radiation would, in the Cretaceous, still have looked fairly similar and 50 years ago would have been assigned to the "transitional shorebirds" which are almost certainly a polyphyletic assemblage of ancestral Neornithes, presbyornithids (or "-oids" in the sense of "wading anseriforms, crown and stem alike", to accomodate the phylogenetic uncertainties), and possibly the occasional paleognath or stem avian too.
BUT:
a) the split of genetic lineages usually pre-dates clearly recognizable morphological distinctness. Even phenotypic variation already present *within* a population *before* it splits into distinct lineages requires some degree of reproductive isolation for being differentially fixed in the daughter populations - think "pheno-sorting" just like genetic lineage sorting. Exceptions are either rare (a mutation that causes a very pronounced morphological change *can* occur at *any* time, but very rarely actually *does* occur at any one *particular* time) or directly related to establishing reproductive isolation between the daughter lineages (and such changes usually affect external morphology, soft-part anatomy, pheromones, bioacoustics, and other sociosexual signals which are largely absent from the fossil record);
b) _Vegavis_ proves that there must have been stem and/or crown galliforms, anseriforms, neoavians, and paleognaths in the Mesozoic. As bronthornithids, odontopterygiforms and gastornithiforms seem to indicate (they are possibly but not *certainly* Galloanseres), these included some anatomically strongly diverging lineages whose known representatives are post-Mesozoic and required comprehensive material and much attention to anatomical detail, careful coding etc to properly evaluate their affinities; thus how stem Galloanseres and ancestral crown Galloanseres looked like - i.e. an understanding of what mix of plesio-and apomorphies they had in the addition to the diagnostic apomorphies of Galloanseres, and how this can confound cladistic analyses - is hard to evaluate: Today's galliforms and anseriforms are highly divergent anatomically due to adaptation to highly dissimilar niches, and judging from the early Pg record of both, this adaptation happened quickly;
c) we do not have much of a paleognath record from the Mesozoic (we have essentially nothing worthwhile *whatsoever* yet), but for all we know, Mesozoic paleognaths were not much less diverse than Mesozoic neognaths and probably did not yet contain "ratites" (paedomorphic flightless and often giant forms) either, meaning it is hard to tell whether a fragmentary "modern-bird-looking" Mesozoic fossil is actually neognath, or one of the Mesozoic paleognaths that are to be expected; and
d) much of the Mesozoic material that is not clearly outside crown Aves is from eastern North America, which was more thoroughly devastated by the K-Pg impact than, say, the Turgai sea region, let alone Antarctica. And while the latter two regions have supplied some of the most intriguing material, they both have severe accessibility issues (post-1990 political fragmentation and defunding of science under pressure of nationalist/religious/isolationist agendas, and a lot of frozen water, respectively).
HOVEVER:
As Longrich et al (2011) prove, a lot of insight can be gained from quantitative analses even of very fragmentary fossils, provided they represents phylogenetically highly informative parts of the skeleton.
And as the case of _Zhylgaia_ (and possibly _Tshulia_) proves, with careful study, even Late Mesozoic fragments of the more diagnostic bones should often provide enough evidence to be identified as neornithean and at least tentatively assignable to a particular lineage.
As distal TMT, proximal humeri, and coracoid heads are quite frequent among the potential crown Aves remains from the Mesozoic, and are character-dense, and in the late Mesozoic would still be comparatively free from profound convergence *between* distant lineages such as the various foot-propelled divers, more comprehensive analyses along the lines of Longrich et al. (2011) should be attempted. Or at least, it's about time for an update to the primarily descriptive/qualitative summary of Hope (2002) - especially the "transitional shorebird" material (see also Mohr 2018:33, Mohr et al. 2021) calls for presentation in a way that allows for easy comparison of all the material.
But it would have to be an internationally coordinated effort, optimally within the larger scope of digitizing collections (for almost anyone, _Gallornis_ still has only a crummy and almost 100 years old photo to go by, but at least the description is now digitized...) so that a comprehensive suite of quantitative morphometric data can be gathered at the same time: I doubt that a single research team could acquire funding to travel to all the places where the pertinent material is held. Hope (2002) was much helped by international relations being at their most relaxed in a long time when she assembled the date. Just 10 years earlier or later, it would have been much more cumbersome if not, for all practical purposes, impossible.
Caveat emptor: _Pixi_ proves that one cannot simply do without a non-avian outgroup when analyzing Mesozoic material just because it "looks avian". But that analysis also proves that a mere avian ulnar fragment carries significant signal already - but *not* phylogenetic, but morphotypical signal: the avians compared to _Pixi_ "claded" according to wing shape/flight mode, not relationships. This which must be considered when interpreting analyses of fragmentary material; unlike strong convergence, the anatomical effects of weaker or more generalized functional demands are less obvious and thus more insidiously confounding. (Loon, grebe and hesperornithean hindlimbs predictably clade as soon as they are not explicitly forbidden from doing so, but *qualitatively* they are easily distinguished even at a superficial glance - the visually conspicuous gross differences are overwhelmed by the sheer number of less-obvious similarities in a quantitative analysis.)
There is also the K-Pg boundary Chatham Islands "large seabird" material announced in the early 21st century. Does anyone know what has become of it (other than _Kupoupou_)? The avifauna of that region was probably less affected by the K-Pg extinction that that of, say, North America and any South American long-distance migrants (hello, _Lamarqueavis_).
The Lance/Hell Creek/Frenchman/Dinosaur Park avifaunas, OTOH, probably came close to being "bullseyed" by the Chicxulub impact's immediate consequences (debris bombardment, tsunami, fires, acid rain); I am skeptical whether any avian lineage (and most other biota) endemic to the general Western Interior Seaway area could persist at all; avian populations that initially did survive in the most devastated regions probably were eventually driven to extinction by or absorbed into the larger and earlier-expanding populations of related taxa from less severely affected regions.
(In that regard, it is probably significant that the procellariiforms are almost certainly secondarily oceanic and derive from littoral ancestors. The oceanic ecosystems must have suffered severe trophic upheaval in the earliest Pg, whereas the shorelines must have been a comparative paradise for anyone who could live on invertebrates and carrion. What was called "transitional shorebirds" was optimally exapted for such a situation, and probably was the most important ecomorph for early-Pg avian survival - but a phylogenetic reality they are not.)
Best,
Eike
References:
* De Souza et al 2023. The Cretaceous Neornithine record and new Vegaviidae specimens from the López de Bertodano Formation (Upper Maastrichthian) of Vega Island, Antarctic Peninsula. An Acad Bras Cienc 8;95(suppl 3):e20230802. doi: 10.1590/0001-3765202320230802. PDF: https://www.scielo.br/j/aabc/a/3mNnMRr8G3NHpKZ4w8K6m8J/?format=pdf&lang=en
* Hope, S. 2002. The Mesozoic record of Neornithes (modern birds). In Mesozoic birds: above the heads of dinosaurs. Edited by L.M. Chiappe and L.M. Witmer. University of California Press, pp. 339–388.
* Longrich, N.R., Tokaryk, T., and Field, D.J. 2011. Mass extinction of birds at the Cretaceous–Paleogene (K–Pg) boundary. Proceedings of the National Academy of Sciences, 108: 15253–15257. PDF: https://www.pnas.org/doi/pdf/10.1073/pnas.1110395108
* Mohr 2018. Cretaceous Bird Fossils of Alberta, Canada. PhD thesis. PDF: https://era.library.ualberta.ca/items/86ac97d2-8425-47b2-9a11-554789d3899a/download/2693bfd2-7ea0-46cb-aba9-e42b485abd27
* Mohr et al 2021. An ornithurine bird coracoid from the Late Cretaceous of Alberta, Canada. Canadian J Earth Scie 58: 134-140. doi: 10.1139/cjes-2019-0202. PDF (preprint): https://www.researchgate.net/profile/Gregory-Funston/publication/342460547_An_ornithurine_bird_coracoid_from_the_Late_Cretaceous_of_Alberta_Canada/links/5f03041445851550508dbba6/An-ornithurine-bird-coracoid-from-the-Late-Cretaceous-of-Alberta-Canada.pdf
Of course we still have the 19th-century "transitional shorebird"/"cimolopterygid" material, much understudied by modern standards, which given the last 3 decades' Canadian finds should urgently be revised and compared especially with these; *all* of it. A Mesozoic gruiform-charadriiform split, for example, or Mesozoic distinctness of the phaetontiforms, or even Mesozoic distinctness of Lari and Charadrii within charadriiforms, is entirely possible. Some degree of radiation within Aequornithes (requiring non-Aequornithes Neoaves as a distinct lineage) in the Mesozoic is also suggested by even the earliest Pg stem penguins being surprisingly derived already. And it is probably safe to say that these most likely candidates for a Mesozoic neoavian radiation would, in the Cretaceous, still have looked fairly similar and 50 years ago would have been assigned to the "transitional shorebirds" which are almost certainly a polyphyletic assemblage of ancestral Neornithes, presbyornithids (or "-oids" in the sense of "wading anseriforms, crown and stem alike", to accomodate the phylogenetic uncertainties), and possibly the occasional paleognath or stem avian too.
BUT:
a) the split of genetic lineages usually pre-dates clearly recognizable morphological distinctness. Even phenotypic variation already present *within* a population *before* it splits into distinct lineages requires some degree of reproductive isolation for being differentially fixed in the daughter populations - think "pheno-sorting" just like genetic lineage sorting. Exceptions are either rare (a mutation that causes a very pronounced morphological change *can* occur at *any* time, but very rarely actually *does* occur at any one *particular* time) or directly related to establishing reproductive isolation between the daughter lineages (and such changes usually affect external morphology, soft-part anatomy, pheromones, bioacoustics, and other sociosexual signals which are largely absent from the fossil record);
b) _Vegavis_ proves that there must have been stem and/or crown galliforms, anseriforms, neoavians, and paleognaths in the Mesozoic. As bronthornithids, odontopterygiforms and gastornithiforms seem to indicate (they are possibly but not *certainly* Galloanseres), these included some anatomically strongly diverging lineages whose known representatives are post-Mesozoic and required comprehensive material and much attention to anatomical detail, careful coding etc to properly evaluate their affinities; thus how stem Galloanseres and ancestral crown Galloanseres looked like - i.e. an understanding of what mix of plesio-and apomorphies they had in the addition to the diagnostic apomorphies of Galloanseres, and how this can confound cladistic analyses - is hard to evaluate: Today's galliforms and anseriforms are highly divergent anatomically due to adaptation to highly dissimilar niches, and judging from the early Pg record of both, this adaptation happened quickly;
c) we do not have much of a paleognath record from the Mesozoic (we have essentially nothing worthwhile *whatsoever* yet), but for all we know, Mesozoic paleognaths were not much less diverse than Mesozoic neognaths and probably did not yet contain "ratites" (paedomorphic flightless and often giant forms) either, meaning it is hard to tell whether a fragmentary "modern-bird-looking" Mesozoic fossil is actually neognath, or one of the Mesozoic paleognaths that are to be expected; and
d) much of the Mesozoic material that is not clearly outside crown Aves is from eastern North America, which was more thoroughly devastated by the K-Pg impact than, say, the Turgai sea region, let alone Antarctica. And while the latter two regions have supplied some of the most intriguing material, they both have severe accessibility issues (post-1990 political fragmentation and defunding of science under pressure of nationalist/religious/isolationist agendas, and a lot of frozen water, respectively).
HOVEVER:
As Longrich et al (2011) prove, a lot of insight can be gained from quantitative analses even of very fragmentary fossils, provided they represents phylogenetically highly informative parts of the skeleton.
And as the case of _Zhylgaia_ (and possibly _Tshulia_) proves, with careful study, even Late Mesozoic fragments of the more diagnostic bones should often provide enough evidence to be identified as neornithean and at least tentatively assignable to a particular lineage.
As distal TMT, proximal humeri, and coracoid heads are quite frequent among the potential crown Aves remains from the Mesozoic, and are character-dense, and in the late Mesozoic would still be comparatively free from profound convergence *between* distant lineages such as the various foot-propelled divers, more comprehensive analyses along the lines of Longrich et al. (2011) should be attempted. Or at least, it's about time for an update to the primarily descriptive/qualitative summary of Hope (2002) - especially the "transitional shorebird" material (see also Mohr 2018:33, Mohr et al. 2021) calls for presentation in a way that allows for easy comparison of all the material.
But it would have to be an internationally coordinated effort, optimally within the larger scope of digitizing collections (for almost anyone, _Gallornis_ still has only a crummy and almost 100 years old photo to go by, but at least the description is now digitized...) so that a comprehensive suite of quantitative morphometric data can be gathered at the same time: I doubt that a single research team could acquire funding to travel to all the places where the pertinent material is held. Hope (2002) was much helped by international relations being at their most relaxed in a long time when she assembled the date. Just 10 years earlier or later, it would have been much more cumbersome if not, for all practical purposes, impossible.
Caveat emptor: _Pixi_ proves that one cannot simply do without a non-avian outgroup when analyzing Mesozoic material just because it "looks avian". But that analysis also proves that a mere avian ulnar fragment carries significant signal already - but *not* phylogenetic, but morphotypical signal: the avians compared to _Pixi_ "claded" according to wing shape/flight mode, not relationships. This which must be considered when interpreting analyses of fragmentary material; unlike strong convergence, the anatomical effects of weaker or more generalized functional demands are less obvious and thus more insidiously confounding. (Loon, grebe and hesperornithean hindlimbs predictably clade as soon as they are not explicitly forbidden from doing so, but *qualitatively* they are easily distinguished even at a superficial glance - the visually conspicuous gross differences are overwhelmed by the sheer number of less-obvious similarities in a quantitative analysis.)
There is also the K-Pg boundary Chatham Islands "large seabird" material announced in the early 21st century. Does anyone know what has become of it (other than _Kupoupou_)? The avifauna of that region was probably less affected by the K-Pg extinction that that of, say, North America and any South American long-distance migrants (hello, _Lamarqueavis_).
The Lance/Hell Creek/Frenchman/Dinosaur Park avifaunas, OTOH, probably came close to being "bullseyed" by the Chicxulub impact's immediate consequences (debris bombardment, tsunami, fires, acid rain); I am skeptical whether any avian lineage (and most other biota) endemic to the general Western Interior Seaway area could persist at all; avian populations that initially did survive in the most devastated regions probably were eventually driven to extinction by or absorbed into the larger and earlier-expanding populations of related taxa from less severely affected regions.
(In that regard, it is probably significant that the procellariiforms are almost certainly secondarily oceanic and derive from littoral ancestors. The oceanic ecosystems must have suffered severe trophic upheaval in the earliest Pg, whereas the shorelines must have been a comparative paradise for anyone who could live on invertebrates and carrion. What was called "transitional shorebirds" was optimally exapted for such a situation, and probably was the most important ecomorph for early-Pg avian survival - but a phylogenetic reality they are not.)
Best,
Eike
References:
* De Souza et al 2023. The Cretaceous Neornithine record and new Vegaviidae specimens from the López de Bertodano Formation (Upper Maastrichthian) of Vega Island, Antarctic Peninsula. An Acad Bras Cienc 8;95(suppl 3):e20230802. doi: 10.1590/0001-3765202320230802. PDF: https://www.scielo.br/j/aabc/a/3mNnMRr8G3NHpKZ4w8K6m8J/?format=pdf&lang=en
* Hope, S. 2002. The Mesozoic record of Neornithes (modern birds). In Mesozoic birds: above the heads of dinosaurs. Edited by L.M. Chiappe and L.M. Witmer. University of California Press, pp. 339–388.
* Longrich, N.R., Tokaryk, T., and Field, D.J. 2011. Mass extinction of birds at the Cretaceous–Paleogene (K–Pg) boundary. Proceedings of the National Academy of Sciences, 108: 15253–15257. PDF: https://www.pnas.org/doi/pdf/10.1073/pnas.1110395108
* Mohr 2018. Cretaceous Bird Fossils of Alberta, Canada. PhD thesis. PDF: https://era.library.ualberta.ca/items/86ac97d2-8425-47b2-9a11-554789d3899a/download/2693bfd2-7ea0-46cb-aba9-e42b485abd27
* Mohr et al 2021. An ornithurine bird coracoid from the Late Cretaceous of Alberta, Canada. Canadian J Earth Scie 58: 134-140. doi: 10.1139/cjes-2019-0202. PDF (preprint): https://www.researchgate.net/profile/Gregory-Funston/publication/342460547_An_ornithurine_bird_coracoid_from_the_Late_Cretaceous_of_Alberta_Canada/links/5f03041445851550508dbba6/An-ornithurine-bird-coracoid-from-the-Late-Cretaceous-of-Alberta-Canada.pdf
Am Dienstag, 17. Juni 2025 um 13:52:31 MESZ hat Alberta Claw <albert...@gmail.com> Folgendes geschrieben:
Thomas Yazbek
Jun 20, 2025, 9:54:09 PMJun 20
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I've always wondered why the 'transitional shorebird' material has never been properly revisited. You'd think with all the attention molecular systematists are paying to the ordinal divergences of Aves, and the better picture we have of galloanseran evolution, there would be more research going on about the topic. I wonder if more answers can come from the European deposits that *Asteriornis* was found in. Not sure how much that part of the Earth was affected by Chicxulub, but it's not politically problematic to conduct field work in Europe.
Thomas Yazbeck
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Cy Marchant
Jun 21, 2025, 2:20:11 AMJun 21
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Alberta Claw
Jun 21, 2025, 8:37:57 AMJun 21
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There is indeed potential for more crown(-like) bird material to come out of the Maastricht Formation—we described a couple of additional fragments in Field et al. (2024). As for the "transitional shorebird" material, I am of course in full agreement that a comprehensive reassessment would be highly desirable. Like Eike mentioned, the resources required to support the necessary scale and scope of comparisons for such a study would likely be a challenge to obtain, especially for fossils that aren't as obviously "high profile" as some of the other material we get to work with nowadays.
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