Limnofregata ("Freshwater frigatebird") is an extinctgenus of primitive frigatebird.[1] The two known species were described after fossils from the Early EoceneGreen River Formation (c.49 million years ago) of Wyoming. A number of good complete and partial skeletons, some with feather impressions, are known of the type species, Limnofregata azygosternon,[2] and L. hasegawai is known from two skulls and most of one torso.
Birds of the genus Limnofregata resembled modern frigatebirds, but had shorter less-hooked bills and longer legs, and longer slitlike nasal openings.[3] They stood 30 to 40 centimetres (12 to 16 in) tall when on the ground and had a wingspan of about 100 to 120 centimetres (3 to 4 ft). The beak was shorter than that of modern frigatebirds, and lacked the typical hook at the end, resembling a strong booby beak more than that of today's frigatebirds. The species differ conspicuously in size, with L. hasegawai being as much larger when compared to L. azygosternon as today's largest species of frigatebird (Fregata magnificens) is compared to the smallest extant one (Fregata ariel). The bill of L. hasegawai was notably larger still than that of its congener, whereas its feet were smaller, echoing a pattern found in the extant Fregata species.
In 2014, a third species, Limnofregata hutchisoni, was described from the Wasatch Formation, 2 million years older than the Green River Formation. Though the only remains are a coracoid and a humerus, these bones clearly identify it as part of the genus. It is of comparable size to F. magnificens. It is at least 53 and possibly 54 or 55 million years old. The fossil beds have remains of crocodiles, large trionychid turtles and fish, indicating a sizeable body of water.[4]
PaleobiologyEdit
Skull of L. hasegawai in the Field Museum.
The Eocene frigatebird genus Limnofregata comprises birds whose fossil remains were recovered from prehistoric freshwater environments, unlike the marine preferences of their modern-day relatives. They are thought to have lived like gulls of the genus Larus.[3] They inhabited the freshwater or brackish lakes that in time formed in today's Green River valley due to the uplift of the Rocky Mountains, feeding on smaller vertebrates and probably harassing other shorebirds for food and feasting on dead fish (e.g. Knightia) during summer dieoffs due to oxygen depletion in the eutrophic lakes. Modern frigatebirds show pronounced sexual dimorphism in size, apparently to avoid competition due to different soaring behavior of male and female wings. As Limnofregata was most likely not a soaring bird, it can be expected that the sexes were much alike. It is not known if the males had a prominent throat balloon for advertising for mates as in their modern relatives, but Limnofregata throat bones differ markedly from those of modern frigatebirds.
ReferencesEdit
^Smith, N. D. (2010). Desalle, Robert (ed.). "Phylogenetic Analysis of Pelecaniformes (Aves) Based on Osteological Data: Implications for Waterbird Phylogeny and Fossil Calibration Studies". PLOS ONE. 5 (10): e13354. Bibcode:2010PLoSO...513354S. doi:10.1371/journal.pone.0013354. PMC2954798. PMID 20976229.
^Olson, Storrs L. (1977). "A Lower Eocene frigatebird from the Green River Formation of Wyoming (Pelecaniformes, Fregatidae)" (PDF). Smithsonian Contributions to Paleobiology. 35 (35): 1–33. doi:10.5479/si.00810266.35.1.
^ abMayr, Gerald (2009). Paleogene Fossil Birds. New York, New York: Springer Science & Business Media. pp. 63–64. ISBN9783540896289.
^Stidham, Thomas A. (2014). "A new species of Limnofregata (Pelecaniformes: Fregatidae) from the Early Eocene Wasatch Formation of Wyoming: implications for palaeoecology and palaeobiology". Palaeontology. 58 (2): 239–249. doi:10.1111/pala.12134. S2CID 85200173.
Olson, Storrs L. & Matsuoka, Hiroshige (2005): New specimens of the early Eocene frigatebird Limnofregata (Pelecaniformes: Fregatidae), with the description of a new species. Zootaxa1046: 1–15.
October 17, 2023
limnofregata, freshwater, frigatebird, extinct, genus, primitive, frigatebird, known, species, were, described, after, fossils, from, early, eocene, green, river, formation, million, years, wyoming, number, good, complete, partial, skeletons, some, with, feath. Limnofregata Freshwater frigatebird is an extinct genus of primitive frigatebird 1 The two known species were described after fossils from the Early Eocene Green River Formation c 49 million years ago of Wyoming A number of good complete and partial skeletons some with feather impressions are known of the type species Limnofregata azygosternon 2 and L hasegawai is known from two skulls and most of one torso LimnofregataTemporal range Early EoceneSkeleton of L azygosternon in the Field Museum of Natural History Scientific classificationDomain EukaryotaKingdom AnimaliaPhylum ChordataClade DinosauriaClass AvesOrder SuliformesFamily FregatidaeSubfamily LimnofregatinaeOlson 1977Genus LimnofregataOlson 1977Species Limnofregata azygosternon type Limnofregata hasegawai Limnofregata hutchisoniDescription EditBirds of the genus Limnofregata resembled modern frigatebirds but had shorter less hooked bills and longer legs and longer slitlike nasal openings 3 They stood 30 to 40 centimetres 12 to 16 in tall when on the ground and had a wingspan of about 100 to 120 centimetres 3 to 4 ft The beak was shorter than that of modern frigatebirds and lacked the typical hook at the end resembling a strong booby beak more than that of today s frigatebirds The species differ conspicuously in size with L hasegawai being as much larger when compared to L azygosternon as today s largest species of frigatebird Fregata magnificens is compared to the smallest extant one Fregata ariel The bill of L hasegawai was notably larger still than that of its congener whereas its feet were smaller echoing a pattern found in the extant Fregata species In 2014 a third species Limnofregata hutchisoni was described from the Wasatch Formation 2 million years older than the Green River Formation Though the only remains are a coracoid and a humerus these bones clearly identify it as part of the genus It is of comparable size to F magnificens It is at least 53 and possibly 54 or 55 million years old The fossil beds have remains of crocodiles large trionychid turtles and fish indicating a sizeable body of water 4 Paleobiology Edit nbsp Skull of L hasegawai in the Field Museum The Eocene frigatebird genus Limnofregata comprises birds whose fossil remains were recovered from prehistoric freshwater environments unlike the marine preferences of their modern day relatives They are thought to have lived like gulls of the genus Larus 3 They inhabited the freshwater or brackish lakes that in time formed in today s Green River valley due to the uplift of the Rocky Mountains feeding on smaller vertebrates and probably harassing other shorebirds for food and feasting on dead fish e g Knightia during summer dieoffs due to oxygen depletion in the eutrophic lakes Modern frigatebirds show pronounced sexual dimorphism in size apparently to avoid competition due to different soaring behavior of male and female wings As Limnofregata was most likely not a soaring bird it can be expected that the sexes were much alike It is not known if the males had a prominent throat balloon for advertising for mates as in their modern relatives but Limnofregata throat bones differ markedly from those of modern frigatebirds References Edit Smith N D 2010 Desalle Robert ed Phylogenetic Analysis of Pelecaniformes Aves Based on Osteological Data Implications for Waterbird Phylogeny and Fossil Calibration Studies PLOS ONE 5 10 e13354 Bibcode 2010PLoSO 513354S doi 10 1371 journal pone 0013354 PMC 2954798 PMID 20976229 Olson Storrs L 1977 A Lower Eocene frigatebird from the Green River Formation of Wyoming Pelecaniformes Fregatidae PDF Smithsonian Contributions to Paleobiology 35 35 1 33 doi 10 5479 si 00810266 35 1 a b Mayr Gerald 2009 Paleogene Fossil Birds New York New York Springer Science amp Business Media pp 63 64 ISBN 9783540896289 Stidham Thomas A 2014 A new species of Limnofregata Pelecaniformes Fregatidae from the Early Eocene Wasatch Formation of Wyoming implications for palaeoecology and palaeobiology Palaeontology 58 2 239 249 doi 10 1111 pala 12134 S2CID 85200173 Olson Storrs L amp Matsuoka Hiroshige 2005 New specimens of the early Eocene frigatebird Limnofregata Pelecaniformes Fregatidae with the description of a new species Zootaxa 1046 1 15 PDF fulltext Retrieved from https en wikipedia org w index php title Limnofregata amp oldid 1149638428, wikipedia, wiki, book, books, library,
