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Tyranni
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| Tyranni Temporal range:
| |
|---|---|
| |
| Dusky-capped flycatcher (Myiarchus tuberculifer) | |
Scientific classification 
| |
| Kingdom: | Animalia |
| Phylum: | Chordata |
| Class: | Aves |
| Order: | Passeriformes |
| Clade: | Eupasseres |
| Suborder: | Tyranni |
| Infraorders | |
The Tyranni (suboscines) are a suborder of passerine birds that includes more than 1,000 species, a large majority of which are South American. It is named after the type genus Tyrannus. These have a different anatomy of the syrinx musculature than the oscines (songbirds of the larger suborder Passeri), hence the common name of suboscines.
The suboscines originated in South America about 50 million years ago[1] and dispersed into the Old World likely via a trans-Atlantic route during the Oligocene.[2] Their presence in the early Oligocene of Europe is well documented by several fossil specimens.[3]
Systematics
[edit]The suborder Tyranni is divided into two infraorders: the Eurylaimides and the Tyrannides. The New Zealand wrens in the family Acanthisittidae are placed in a separate suborder Acanthisitti.[4]
The phylogenetic relationships of the 16 families in the Tyranni suborder is shown below. The cladogram is based on a large molecular genetic study by Carl Oliveros and collaborators published in 2019:[4] The families and the species numbers are from the list maintained by the International Ornithologists' Union (IOC).[5]
| Tyranni |
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The Eurylaimides contain the Old World suboscines – mainly distributed in tropical regions around the Indian Ocean – and a single American species, the sapayoa:[4]
- Philepittidae: asities
- Eurylaimidae: typical broadbills
- Calyptomenidae: African and green broadbills
- Sapayoidae: broad-billed sapayoa
- Pittidae: pittas
The Tyrannides contain all the suboscines from the Americas except the broad-billed sapayoa. The families listed here are those recognised by the International Ornithologists' Union.[5]
- Pipridae: manakins
- Cotingidae: cotingas
- Tityridae: tityras, sharpbill, becards (includes Oxyruncus and Onychorhynchus)
- Tyrannidae: tyrant-flycatchers (includes Piprites, Platyrinchus, Tachuris and Rhynchocyclus)
- Melanopareiidae: crescent chests
- Conopophagidae: gnateaters and gnatpittas
- Thamnophilidae: antbirds
- Grallariidae: antpittas
- Rhinocryptidae: tapaculos
- Formicariidae: antthrushes
- Furnariidae: ovenbirds and woodcreepers (includes Dendrocolaptidae)
This group has been separated into three parvorders by Sibley & Ahlquist. However, DNA:DNA hybridization did not reliably resolve the suboscine phylogeny. It was eventually determined that there was a simple dichotomy between the antbirds and allies (tracheophones), and the tyrant-flycatchers and allies.[6] Given that the "parvorder" arrangement originally advanced is obsolete (see e.g. Irestedt et al. 2002 for tracheophone phylogeny) — more so if the Eurylaimides are elevated to a distinct suborder — it is better to rank the clades as superfamilies or, if the broadbill group is considered a separate suborder, as infraorders. In the former case, the name Furnarioidea would be available for the tracheophones, whereas "Tyrannoidea", the "bronchophone" equivalent, has not yet been formally defined.[7] In the latter case, the tracheophones would be classified as "Furnariides",[8] while the Tyrannides would be restricted to the tyrant-flycatchers and other "bronchophone" families.
The tracheophones contain the Furnariidae, Thamnophilidae, Formicariidae (probably including most tapaculos), and Conopophagidae. The tyrant-flycatcher clade includes the namesake family, the Tityridae, the Cotingidae, and the Pipridae.
References
[edit]- ^ Claramunt, S.; Cracraft, J. (2015). "A new time tree reveals Earth history's imprint on the evolution of modern birds". Science Advances. 1 (11) e1501005. Bibcode:2015SciA....1E1005C. doi:10.1126/sciadv.1501005. PMC 4730849. PMID 26824065.
- ^ Selvatti, A. P.; Galvão, A.; Mayr, G.; Miyaki, C. Y.; Russo, C A. de Moraes (2022). "Southern hemisphere tectonics in the Cenozoic shaped the pantropical distribution of parrots and passerines". Journal of Biogeography. 49 (10): 1753–1766. Bibcode:2022JBiog..49.1753S. doi:10.1111/jbi.14466.
- ^ Bochenski, Z. M.; Tomek, T.; Bujoczek, M.; Salwa, G. (2021). "A new passeriform (Aves: Passeriformes) from the early Oligocene of Poland sheds light on the beginnings of Suboscines". Journal of Ornithology. 162 (2): 593–604. Bibcode:2021JOrni.162..593B. doi:10.1007/s10336-021-01858-0.
- ^ a b c Oliveros, C.H.; et al. (2019). "Earth history and the passerine superradiation". Proceedings of the National Academy of Sciences of the United States of America. 116 (16): 7916–7925. Bibcode:2019PNAS..116.7916O. doi:10.1073/pnas.1813206116. PMC 6475423. PMID 30936315.
- ^ a b Gill, Frank; Donsker, David; Rasmussen, Pamela, eds. (January 2023). "Family Index". IOC World Bird List Version 13.1. International Ornithologists' Union. Retrieved 5 March 2023.
- ^ A conceivable vernacular name would be "bronchophones". This would parallel the German vernacular names, Luftröhrenschreier (tracheophones) and Bronchienschreier (bronchophones).
- ^ And thus should not be used without quotation marks.
- ^ See remark at "Tyrannoidea". This peculiarity is explained by the fact that Sibley & Ahlquist's analyses erroneously suggested an overly complex phylogeny for the tracheophones, and a much simpler one for the tyrant-flycatchers and allies.
Further reading
[edit]- Ohlson, J.I.; Irestedt, M.; Ericson, P.G.P.; Fjeldså, J. (2013). "Phylogeny and classification of the New World suboscines (Aves, Passeriformes)". Zootaxa. 3613 (1): 1–35. doi:10.11646/zootaxa.3613.1.1. PMID 24698900.
- Irestedt, Martin; Fjeldså, Jon; Johansson, Ulf S. & Ericson, Per G.P. (2002): Systematic relationships and biogeography of the tracheophone suboscines (Aves: Passeriformes). Molecular Phylogenetics and Evolution 23(3): 499–512. doi:10.1016/S1055-7903(02)00034-9 (HTML abstract)
- Selvatti, A.P.; Galvão, A.; Pereira, A.G.; Pedreira Gonzaga, L.; Russo, C.A.D.M. (2017). "An African origin of the Eurylaimides (Passeriformes) and the successful diversification of the ground-foraging pittas (Pittidae)". Molecular Biology and Evolution. 34 (2): 483–499. doi:10.1093/molbev/msw250. PMID 28069777.
Tyranni
View on Grokipediafrom Grokipedia
Tyranni, also known as suboscines, is a suborder of passerine birds within the order Passeriformes, encompassing approximately 1,300 species that are distinguished from the oscine suborder by their simpler syrinx structure, which limits vocal complexity and learning capabilities.[1][2][3][4]
This suborder represents a major clade in avian evolution, originating from early passerine radiations and exhibiting high diversity in tropical habitats, with over 80% of species concentrated in the Neotropics of South and Central America.[1][5] Taxonomic classifications, advanced by molecular phylogenetic studies following pioneering DNA-DNA hybridization work, divide Tyranni into two main infraorders: Eurylaimides (Old World broadbills, pittas, and asities) and Tyrannides (New World tyrant flycatchers, antbirds, ovenbirds, and related families); the New Zealand wrens (family Acanthisittidae) form a separate suborder, Acanthisitti, basal to Tyranni and oscines.[1][6] Key families such as Tyrannidae (over 440 species of flycatchers) and Furnariidae (ovenbirds and woodcreepers, around 320 species) dominate the Neotropical avifauna, contributing to the suborder's role as a biodiversity hotspot in ecosystems like Amazonian rainforests.[7][8][9][10]
Ecologically, Tyranni species occupy diverse niches, from insectivorous flycatching to ground-foraging and leks in manakins, with many exhibiting cryptic plumage or specialized behaviors adapted to dense understories.[5][3] Phylogenetic analyses confirm their monophyly and basal position relative to oscines, underscoring ancient divergences estimated at 40-50 million years ago.[11] Conservation challenges include habitat loss in tropical regions, affecting numerous endemic species.[6]
Taxonomy and Systematics
Classification History
The classification of Tyranni, a suborder of passerine birds commonly known as suboscines, originated in the early 19th century with William Swainson's establishment of the family Tyrannidae in 1837, named after the genus Tyrannus and initially positioned within the order Passeriformes based on morphological similarities in perching and bill structure.[12] This early framework grouped many New World flycatcher-like birds together, but lacked a clear distinction from the oscine songbirds, often treating them as a subset or allied group within broader passerine categories without recognizing deeper anatomical differences. Throughout the 19th and early 20th centuries, classifications varied, with some ornithologists integrating Tyranni into the Oscines (songbirds) due to superficial resemblances in habitat and behavior, while others began separating them based on emerging anatomical evidence, particularly syringeal structure. A pivotal advancement came in 1971 with Peter L. Ames' detailed study of syrinx musculature, which demonstrated that suboscines possess a simpler syringeal anatomy with fewer intrinsic muscles (typically three pairs) compared to the more complex, up to nine pairs in oscines, thereby justifying Tyranni as a distinct suborder from the song-learning Passeri.[13] In the late 20th century, molecular approaches revolutionized the understanding of Tyranni through Charles G. Sibley and Jon E. Ahlquist's extensive DNA-DNA hybridization studies, published in 1990, which elevated Tyranni to a parvorder within Passeriformes and controversially included both New World suboscines and Old World groups like broadbills (Eurylaimides) in a broader assemblage, reflecting perceived genetic affinities. However, this scheme, while influential for its scale, has since been deemed obsolete due to limitations in hybridization resolution and inconsistencies with subsequent data. The transition to modern molecular phylogenetics in the 2000s solidified Tyranni's monophyly through sequence-based analyses, with F. Keith Barker and colleagues' 2004 study using nuclear genes RAG-1 and RAG-2 across 45 passerine families confirming the suborder's unity as a basal clade to the oscines, excluding the Old World elements from Sibley and Ahlquist's parvorder and emphasizing New World origins.[14] This work marked a shift toward gene-sequence phylogenies, providing robust support for syringeal distinctions and resolving longstanding debates on suboscine relationships.Current Classification
The suborder Tyranni, comprising the suboscines, is recognized as one of the two primary suborders within the order Passeriformes, positioned as the sister group to the oscines (suborder Passeri). This placement is supported by comprehensive phylogenomic analyses that establish the monophyly of both suborders and their divergence early in passerine evolution. Note that the New Zealand wrens (family Acanthisittidae) form a separate suborder Acanthisitti, distinct from Tyranni, based on recent phylogenomic studies, though older schemes included them within Tyranni.[15] Modern taxonomy divides Tyranni into two infraorders: Eurylaimides and Tyrannides. Eurylaimides encompasses the Old World suboscines, including five families distributed primarily in tropical Asia, Africa, and Madagascar, with the notable exception of the monotypic Sapayoa (Sapayoa aenigma) in Central and South America; representative families include Pittidae (44 species, such as pittas) and Eurylaimidae (14 species, broadbills). Tyrannides, restricted to the New World, is further subdivided into two parvorders: Tyrannida, containing seven families such as Tyrannidae (447 species, tyrant flycatchers), and Furnariida, with four families including Furnariidae (315 species, ovenbirds and allies).[15] This classification framework is based on a robust phylogeny derived from 809 nuclear loci across 363 bird species, which resolved deep relationships within Tyranni and confirmed the monophyly of its major clades with high support. In total, the suborder includes 16 families and over 1,000 species, as enumerated in the IOC World Bird List (version 13.2, 2023; updated in subsequent versions without major changes to Tyranni totals).[15]Physical Characteristics
Morphology
Tyranni birds exhibit a general body plan typical of small to medium-sized passerines, with lengths ranging from approximately 6.5–7 cm in the smallest tyrant flycatchers, such as the black-capped pygmy-tyrant (Myiornis atricapillus), to 30 cm in larger broadbills and antbirds, featuring compact bodies, short necks, and robust legs suited for perching on branches.[16][17][18] This structure supports their primarily arboreal lifestyles in forested environments across tropical regions.[19] Bill morphology in the Tyranni shows considerable variation adapted to diverse foraging strategies, particularly insectivory. In the Old World broadbills (Eurylaimidae), bills are characteristically broad, flat, and wide-gaped, often with bristles at the base to aid in capturing prey amid foliage.[17] New World antbirds (Thamnophilidae) possess stout, hooked bills ideal for gleaning insects from vegetation or probing leaf litter.[18] Similarly, tyrant flycatchers (Tyrannidae) feature short, wide bills, sometimes with a slight hook and prominent rictal bristles, facilitating aerial insect capture through sallying flights.[20] Plumage in Tyranni species is diverse, often serving camouflage needs, with many New World taxa displaying cryptic patterns of grays, browns, whites, and rufous tones to blend into forest understories.[21][22] In contrast, some Old World representatives, such as pittas (Pittidae), exhibit brighter, more vibrant colorations including iridescent blues, greens, and reds. Sexual dimorphism in plumage is generally minimal compared to oscine passerines, though it occurs in certain families with males showing more contrasting patterns.[23] Wings in Tyranni are typically rounded or elliptical, promoting maneuverability for navigating dense vegetation, while tails vary from short and square to elongated in species like manakins (Pipridae), where extended central feathers enhance visual displays.[24][25][26]Syrinx and Vocalization
The syrinx in Tyranni, the suboscine passerines, exhibits a simpler anatomical structure than that of oscines, characterized by 1–2 pairs of intrinsic syringeal muscles inserted primarily on the bronchial semi-rings, enabling basic control over sound production but lacking the intricate muscular complexity required for vocal learning. In contrast, oscines possess 4–9 pairs of such muscles, allowing for precise modulation of syringeal membranes to produce learned songs.[27] This reduced musculature in Tyranni—varying slightly across families, with 2 pairs in Tyrannidae and Furnariidae, and 1 pair in Formicariidae—results in a mesomyodian configuration where muscles insert unequally on dorsal and ventral elements, supporting innate rather than culturally transmitted vocalizations. Vocalizations in Tyranni are predominantly innate and structurally simple, consisting of unlearned calls or short songs such as whines, buzzes, and trills that serve communicative functions without the need for imitation or practice. For instance, members of the Tyrannidae family, like the great crested flycatcher (Myiarchus crinitus), produce sharp, high-pitched "whit" or "wheep" calls that are species-specific and genetically determined from hatching. Similarly, antbirds in the Thamnophilidae (e.g., the chestnut-backed antbird Poliocrania exsul) employ duet-like vocalizations, where males and females alternate or overlap notes in coordinated sequences to defend territories, reflecting an instinctive rather than learned pattern.[28] Some species, such as manakins in the Pipridae family, supplement syringeal sounds with non-vocal mechanical noises generated by wing feathers during displays, producing buzzing or snapping tones independent of the syrinx.[29] This anatomical simplicity and reliance on innate vocal production in Tyranni provide a valuable model for investigating the evolutionary distinction between genetically programmed signals and learned ones, highlighting how reduced syringeal control correlates with minimal vocal plasticity across avian lineages.[30]Distribution and Habitat
Geographic Distribution
The suborder Tyranni encompasses approximately 1,300 species of suboscine passerine birds, with the vast majority—over 80%—confined to the Neotropical region of South and Central America. This dominance reflects the group's evolutionary stronghold in the Americas, where species richness peaks in the Amazon Basin, a global hotspot for avian diversity that supports more than 230 species in the antbird family Thamnophilidae alone.[31][32] The Old World contingent includes the infraorder Acanthisittides (New Zealand wrens, 2 species, endemic to New Zealand and nearby islands) and the clade Eurylaimides (approximately 70 species distributed across tropical Southeast Asia, sub-Saharan Africa, and Australasia). Pittas (family Pittidae), a prominent group within Eurylaimides, range from India through Southeast Asia, New Guinea, and northern Australia, often in forested understories. An enigmatic New World outlier in this clade is the broad-billed sapayoa (Sapayoa aenigma), a monotypic species restricted to lowland rainforests from Panama eastward to western Colombia and extreme northwestern Ecuador.[33][34][35] Tyranni are absent as breeding species from temperate zones of North America and Europe, though occasional vagrants, such as the fork-tailed flycatcher (Tyrannus savana), reach southern North America from their Neotropical breeding grounds. The group's biogeographic patterns stem from ancient dispersals, including a post-Oligocene trans-Atlantic colonization event that established the Eurylaimides outlier Sapayoa in the New World from Old World ancestors.[33]Habitat Preferences
Tyranni species predominantly occupy tropical forest habitats across the Neotropics and Southeast Asia, with many favoring the understory and midstory layers of rainforest where dense vegetation provides cover for foraging and nesting. Antbirds of the family Thamnophilidae, for instance, are characteristic understory inhabitants of humid lowland forests, often following army ant swarms to capture prey in the leaf litter and low shrubs.[36] In contrast, numerous tyrant flycatchers in the family Tyrannidae exploit the forest canopy or edges, perching high to sally for aerial insects, reflecting a diversification in vertical niches that reduces competition within the suborder.[37] While tropical forests dominate, some Tyranni extend into more open environments, including savannas and mangroves, where species like certain flycatchers adapt to edge habitats and second-growth woodlands regenerating after disturbance.[37] Vertical stratification is particularly pronounced among New World Tyranni, enabling coexistence in layered forest environments. Ground-foraging gnateaters (Conopophagidae) remain close to the forest floor in the understory of lowland and montane tropical forests, lunging at insects from low perches or directly from the leaf litter, which suits their short tails and long legs for navigating dense undergrowth.[38] Aerial insectivores in Tyrannidae, however, prefer open strata above the canopy or in clearings, using agile flight to pursue flying prey, a behavioral adaptation that distinguishes them from more terrestrial relatives.[37] This partitioning underscores the suborder's ecological flexibility within forested systems. Certain Tyranni lineages exhibit specialized adaptations to non-forest habitats, expanding beyond humid tropics. Within the Furnariida clade, ovenbirds (Furnariidae) occupy arid scrub and thorn-scrub regions, where they construct durable mud nests—often dome-shaped and attached to rocks or branches—to withstand dry conditions and predation.[39] Old World broadbills (Eurylaimidae) are confined to humid lowland forests of Southeast Asia, inhabiting the subcanopy of evergreen broad-leaved woodlands where their broad bills aid in gleaning fruits and insects from foliage. These adaptations highlight the suborder's radiation into varied microhabitats, from arid puna grasslands to peat swamps. Many Tyranni species show high sensitivity to habitat fragmentation, requiring large tracts of contiguous forest to maintain viable populations and contributing to patterns of local endemism. Suboscines, including understory specialists like antbirds and gnateaters, often decline in fragmented landscapes due to reduced prey availability and increased edge effects, with studies identifying over half of recorded species as highly sensitive in Neotropical forests.[40] This vulnerability fosters endemism in isolated forest patches, particularly among forest-interior dwellers that avoid crossing open gaps.[41]Behavior and Ecology
Foraging and Diet
The Tyranni, comprising over 1,300 species of suboscine passerines, are predominantly insectivorous, relying primarily on arthropods such as insects, spiders, and myriapods for their diet. This dietary focus supports their ecological role as key arthropod predators in Neotropical and Indo-Malayan forests, understories, and open habitats, where they help regulate invertebrate populations. Foraging strategies vary widely across families, reflecting adaptations to diverse microhabitats; for instance, many Tyrannidae (tyrant flycatchers) employ sallying, launching aerial pursuits (hawking) from perches to capture flying insects like beetles, bees, and homopterans, often accounting for the bulk of their intake.[42] In contrast, Rhinocryptidae (tapaculos) probe the ground litter with their bills to glean hidden annelids and arthropods, hopping or walking through moss and leaf debris.[43] Social foraging enhances prey access in certain lineages, notably within Thamnophilidae (antbirds), where species like those in the genus Thamnophilus trail army ant swarms (Eciton burchellii) to exploit flushed invertebrates, a behavior known as ant-following.[44] This obligate or facultative strategy, evolved convergently multiple times, with birds using vocal cues and visual signals to join multi-species flocks at raid fronts.[44] Gleaning from foliage or bark is common in antbirds and other understory dwellers, targeting camouflaged prey like caterpillars and orthopterans. While primarily arthropod-focused, some Tyranni exhibit omnivorous tendencies; for example, certain Furnariidae (ovenbirds and woodcreepers) supplement their insect diet with seeds, fruits, and occasionally small vertebrates like lizards or frogs, adapting to seasonal resource availability.[45] Similarly, Old World Pittidae (pittas) consume earthworms, snails, and insects but opportunistically take small vertebrates such as frogs or skinks, probing leaf litter on forest floors.[46] Morphological traits strongly correlate with these foraging methods, enabling niche partitioning within Tyranni communities. Bill shape is particularly diagnostic: wide, flattened bills in many Tyrannidae facilitate hawking aerial insects by aiding maneuverability and prey interception, while slender, curved bills in some Furnariidae suit probing crevices for hidden arthropods.[47] Leg and foot adaptations further support ground-based foraging in tapaculos and ovenbirds, with robust tarsi allowing stable probing in dense undergrowth. These ecomorphological specializations underscore the Tyranni's radiation into varied trophic roles, from canopy sallying to terrestrial scavenging.[47]Reproduction
Members of the Tyranni predominantly form socially monogamous pairs for breeding, with both partners sharing parental duties, though exceptions occur in families like the Pipridae, where lekking systems prevail.[48] In manakins (Pipridae), males aggregate at leks to perform cooperative or solitary visual and vocal displays, attracting females who mate polygynously but rear offspring alone; cooperative breeding is rare throughout the suborder.[49][50] Nest architecture varies extensively across Tyranni families, reflecting adaptive diversity. Tyrannidae typically construct open, cup-shaped nests from plant fibers, moss, and lichens, placed in tree forks or on branches at moderate heights.[51] Furnariidae exhibit the broadest range of nest types among birds, including domed or tubular structures woven from grass and sticks, often concealed in cavities or vegetation; ovenbirds (e.g., Furnarius rufus) build prominent mud "ovens" on the ground or low perches.[52] Some tapaculos in the Rhinocryptidae construct bulky, domed ground nests from roots and leaves, hidden under vegetation or in burrows.[53] Clutch sizes in Tyranni generally comprise 2–4 eggs, laid at intervals of one per day until completion.[54] Incubation, lasting 14–20 days, is typically biparental in monogamous species, with females often taking the primary role at night; in lekking Pipridae, females incubate solo.[55] Nestlings fledge after 10–21 days, during which both parents (or the female alone in polygynous systems) provision food, leading to high fledging success in protected nests.[55] Vocalizations play a key role in Tyranni reproduction, primarily through innate calls for territory establishment and mate attraction rather than learned songs.[56] These simple, stereotyped calls—often sharp or buzzing—facilitate pair coordination and lek signaling, with minimal vocal learning observed compared to oscine passerines.[57] In lekking manakins, displays combine innate calls with physical movements to enhance mating success.[49]Evolutionary History
Origins and Phylogeny
The Tyranni, or suboscines, represent a monophyletic suborder within the Passeriformes, serving as the sister group to the oscine suborder Passeri, with their divergence estimated around 44 million years ago during the Middle Eocene. This split marks a fundamental division in passerine evolution, with Tyranni characterized by distinct vocal and morphological traits diverging from the more complex song repertoires of Passeri. Stem passerines, including early Tyranni lineages, are inferred to have originated in South America approximately 50 million years ago, during the Eocene to Oligocene transition, aligning with the fragmentation of Gondwana and the isolation of southern continents.[58] Key early divergences within Tyranni include the split between Eurylaimides and Tyrannides around 43 million years ago in the mid-Eocene, with Eurylaimides radiating into the Old World, particularly Africa and Asia, approximately 40 million years ago, while Tyrannides remained confined to the Americas following Gondwanan separation.[58] The crown age of Tyranni is dated to about 39 million years ago in the Late Eocene, supported by comprehensive multi-locus molecular analyses that integrate nuclear and mitochondrial data across thousands of species. These phylogenies, such as the time-calibrated tree in Jetz et al. (2012), reveal a biogeographic history deeply intertwined with tectonic events, including the uplift of the Andes around 20-30 million years ago and the dynamic formation of the Amazon basin, which facilitated habitat diversification and lineage isolation within Tyrannides. A notable superradiation within Tyranni occurred between 30 and 40 million years ago, coinciding with global cooling during the Eocene-Oligocene transition and associated habitat shifts from tropical forests to more fragmented ecosystems, driving adaptive radiations in both Eurylaimides and Tyrannides. This burst of diversification is evidenced by elevated net diversification rates in molecular timetrees, reflecting responses to climatic cooling and the emergence of new ecological niches, though direct fossil timelines provide additional calibration points for these inferences.Fossil Record
The fossil record of Tyranni remains sparse and fragmentary, with most known specimens consisting of isolated bones rather than complete skeletons, reflecting challenges in preservation and discovery. Approximately 20 taxa have been described to date, primarily from the Paleogene and Neogene periods, providing limited but crucial insights into the temporal and geographic distribution of this clade. The absence of confirmed Tyranni fossils from the Eocene underscores significant gaps in the early history, as the clade's diversification is inferred to predate the Oligocene based on the stratigraphic context of available material. The earliest definitive fossils of Tyranni originate from the early Oligocene of Europe, dating to approximately 30–34 million years ago (mya), and represent basal suboscines. Notable among these is Wieslochia weissi from the Rupelian stage (early Oligocene) of Frauenweiler, Germany, known from multiple specimens including a partial skeleton that exhibits a well-developed tuberculum ligamenti collateralis ventralis on the os coracoid, a synapomorphy of Tyranni.[59] Additional early Oligocene records include a small suboscine-like passeriform from the Luberon region of France, represented by wing elements assignable to Tyrannida, and articulated remains from Menilitic shales in Poland that display osteological features such as a fenestra synovialis in the os tibiotarsus, further supporting a European presence of early Tyranni.[60][61] These European fossils, around 34 mya, provide evidence for trans-Atlantic dispersal events that introduced Tyranni to the Old World from their likely South American origins.[33] In the New World, the fossil record is even more limited due to taphonomic biases in tropical environments, where acidic soils and dense vegetation hinder preservation. The oldest South American Tyranni fossils date to the early Miocene, such as a partial passeriform skeleton from the Gaiman Formation in Patagonia, Argentina (approximately 20 mya), which exhibits traits suggestive of suboscines within Tyranni, including a short and robust tarsometatarsus.[62] Later Miocene records from the same region include additional fragmentary elements potentially allied with tyrannids, indicating a growing diversity of Tyranni in South America by the Neogene, though specific affinities remain tentative due to incompleteness. Old World records beyond Europe are scarce, with Oligocene and Miocene fossils primarily from Asia featuring broadbill-like forms within Eurylaimides. A partial passerine skeleton from the early to middle Miocene of Japan represents one of the earliest Asian records, though its precise placement within Tyranni is unresolved; putative broadbill relatives are also noted from Miocene deposits, supporting the persistence of Eurylaimides lineages in Southeast Asia.[64] Overall, the fragmentary nature of these ~20 described specimens highlights the need for further discoveries to fill temporal gaps, particularly in the Eocene and tropical New World.[65]Conservation
Threats
Habitat loss, primarily driven by deforestation in the Amazon Basin, represents the most significant threat to Tyranni populations, with roughly 20% of the original forest cover lost since the 1970s through agricultural expansion, logging, and infrastructure development.[66] This extensive degradation affects many Tyranni species that depend on intact forest ecosystems, particularly understory-dwelling specialists such as antbirds in the family Thamnophilidae, which require large, continuous tracts for foraging on army ant swarms.[67] Habitat fragmentation exacerbates these impacts by isolating populations, reducing genetic diversity, and disrupting mixed-species flocks critical for predator avoidance and resource access in species like scale-backed antbirds (Willisornis poecilinotus).[68] The October 2025 IUCN Red List update assesses all 11,185 bird species worldwide, finding 11.5% globally threatened and 61% in decline, trends driven largely by habitat loss and agriculture that particularly impact Neotropical Tyranni.[69] Climate change further compounds habitat pressures by shifting tropical ranges and intensifying droughts in savanna and semi-arid environments favored by members of the Furnariidae family, such as ovenbirds and woodcreepers.[70] Projections indicate severe range contractions for many woodcreeper species, with up to 80% potential loss in suitable habitat in regions like Mexico due to altered precipitation patterns and temperature increases.[71] These changes not only limit breeding and foraging areas but also heighten vulnerability to secondary stressors like wildfires in fragmented landscapes. Additional anthropogenic pressures include hunting and illegal trade targeting Asian pittas (Pittidae), where capture for the pet market has decimated populations of species like the fairy pitta (Pitta nympha) and Gurney's pitta (Pitta gurneyi).[72] Widespread pesticide use, particularly neonicotinoids, reduces insect prey abundance for insectivorous Tyranni such as tyrant flycatchers (Tyrannidae), leading to reproductive failures and population declines in grassland and forest-edge species like the black phoebe (Sayornis nigricans).[73] On islands in Southeast Asia, invasive species like rats prey on eggs and nestlings of ground-nesting pittas, amplifying extinction risks for insular populations.[74] Overall, these threats have elevated conservation concerns across the suborder; within Tyrannidae alone, as of 2020, 80 species (about 20% of the family) are categorized as Near Threatened or higher, including 11 Endangered and 1 Critically Endangered.[75]Conservation Measures
Protected areas play a crucial role in safeguarding the diverse habitats of Tyranni, particularly in the Neotropics where most species occur. Yasuní National Park in Ecuador stands out as a premier site for conserving Amazonian biodiversity, encompassing over 600 bird species, many of which are Tyranni suboscines such as antbirds (Formicariidae) and ovenbirds (Furnariidae), contributing to the park's status as one of the world's most biodiverse regions.[76] Similarly, the Discovery Coast Atlantic Forest Reserves in Brazil protect endemic Tyranni in one of the most threatened biomes, including species like the Alagoas foliage-gleaner (Philydor novaesi) from the Furnariidae family, through a network of 25 protected areas spanning 1.3 million hectares focused on forest preservation and research.[77] International conservation initiatives further support Tyranni protection. BirdLife International monitors numerous Tyranni species via its DataZone platform, providing population assessments and threat analyses for over 400 tyrant flycatchers (Tyrannidae) and related families, enabling targeted interventions across their ranges.[78] Although few Tyranni species are directly regulated under CITES due to limited international trade, assessments highlight potential risks for some, informing broader wildlife trade policies. Research and restoration efforts enhance these protections. Molecular taxonomic studies, such as DNA barcoding of Brazilian tyrant flycatchers, refine species identifications in the Atlantic Forest and Cerrado, facilitating precise conservation planning for cryptic or newly delimited taxa.[79] In Brazil, reforestation projects in the Atlantic Forest have improved habitat connectivity for mesophilic birds, including Furnariidae, by restoring forest corridors that reverse fragmentation effects and support population viability.[80] Notable successes demonstrate the efficacy of these measures. Habitat corridor restoration has led to population recoveries in flycatchers like the southwestern willow flycatcher (Empidonax traillii extimus), with increased nesting in rehabilitated riparian zones along streams in the southwestern United States, as documented in long-term recovery plans.[81][82] Globally, the 30x30 initiative aims to protect at least 30% of land and oceans by 2030, including Neotropical forests critical for Tyranni, with endorsements from over 100 countries to expand protected areas and combat deforestation.[83]References
- https://www.[researchgate](/page/ResearchGate).net/publication/376077487_New_fossil_birds_from_the_Miocene_of_Patagonia