incertae sedis

Apatornithiformes Martin, 1991
Apatornithidae Furbringer, 1888
Apatornis Marsh, 1873b
Definition- (Apatornis celer <- Ichthyornis dispar, Struthio camelus, Tetrao major, Vultur gryphus) (modified from Clarke, 2004)
= Iaceornis sensu Clarke, 2004
Definition- (YPM 1451 <- Ichthyornis dispar, Struthio camelus, Tetrao major, Vultur gryphus)
Comments- Clarke (2004) accidentally defined Iaceornis identically to Apatornis.
Brodkorb (1963) referred Cimolopteryx retusus to Apatornis, but transferred it to a new genus Palintropus in 1970.
References- Marsh, 1873b. On a new sub-class of fossil birds (Odontornithes). American Journal of Science, 3rd series. 5, 161-162.
Furbringer, 1888. Untersuchungeb zur Morphologie und Systematik der Vogel. Amsterdam: Holkema, 1751 pp.
Brodkorb, 1963. Birds from the Upper Cretaceous of Wyoming. In Sibley, Hickey and Hickey (eds). Proceedings of the XIII International Ornithological Congress. 55-70.
Brodkorb, 1970. The generic position of a Cretaceous bird. Quarterly Journal of the Florida Academy of Science. 32(3), 239-240.
Martin, 1991. Mesozoic birds and the origin of birds. in Schultze and Trueb (eds). Origins of the Higher Groups of Tetrapods: Controversy and Consensus. 485-540.
Clarke, 2004. Morphology, phylogenetic taxonomy, and systematics of Ichthyornis and Apatornis (Avialae: Ornithurae). Bulletin of the American Museum of Natural History. 286: 1-179.
A. celer (Marsh, 1873a) Marsh, 1873b
Definition- (the species that includes YPM 1451) (Clarke, 2004)
= Ichthyornis celer Marsh, 1873a
Early Campanian, Late Cretaceous
Hesperornis Zone of the Smoky Hill Chalk Member of the Niobrara Formation, Kansas, US
Holotype- (YPM 1451) posterior synsacrum
Other diagnoses- Marsh (1873a) originally diagnosed Ichthyornis celer by contrasting it to Ichthyornis dispar. He stated it was larger, but this doesn't seem to be the case and he changed his mind by 1875. Marsh also stated the synsacrum was more slender than I. dispar, with a more concave posterior articular surface, but Clarke (2004) noted these differences don't seem to exist. Shufeldt (1915) noted the slender appearence was due to transverse crushing and a broken ventral edge.
Marsh (1880) later proposed additional differences from Ichthyornis. The synsacrum must contain at least one additional vertebra than the ten seen in the I. dispar holotype, but a specimen referred to I. victor (YPM 1732) has twelve vertebrae, and Aves basally have more vertebrae than the I. dispar holotype too. The presence of four mid sacral vertebrae with dorsally directed transverse processes (as opposed to Ichthyornis' three) is also seen in most Aves. Finally, Apatornis differs in lacking ossified tendons on its sacral vertebrae, but this is a plesiomorphy shared by almost all non-avian theropods.
Comments- The holotype was discovered in 1872 and described by Marsh (1873a) as a new species of Ichthyornis. He placed it in a new genus later that year without justification and described it in more detail in 1880. The partial skeleton YPM 1734 was referred to Apatornis by Marsh (1880), and most opinions on this taxon since 1880 have been based on this skeleton instead of the holotype synsacrum. Shufeldt (1915) believed the holotype belonged to a species of Ichthyornis, though without listed evidence. Howard (1955) thought the transversely narrow synsacrum which was unfused to the pelvis was similar to Telmabates (now recognized as a presbyornithid anatiform), but the sacrum is crushed transversely and the lack of fusion is primitive and also found in most Mesozoic ornithuromorphs, charadriiforms and other taxa. Martin (1987) described cervical and humeral characters of Apatornis, but these elements are not preserved in the holotype or YPM 1734. Elzanowski (1995) and Hope (2002) noted the problem that YPM 1734 was not comparable with the type, which was solved when Clarke (2002, 2004) separated the skeleton as the new taxon Iaceornis marshi. Clarke found Apatornis to be more derived than Ichthyornis based on the presence of four or more sacrals with dorsally directed transverse processes, but less derived than Aves due to the presence of thirteen or less sacrals. However, a similarly low number of sacral vertebrae is present in many avians, including many procellariiforms, charadriiforms and most of the 'higher land birds'. As Clarke did not include any neoavians in her analysis, it seems possible Apatornis could belong to that clade.
References- Marsh, 1873a. Notice of a new species of Ichthyornis. American Journal of Science, 3rd series. 5, 74.
Marsh, 1873b. On a new sub-class of fossil birds (Odontornithes). American Journal of Science, 3rd series. 5, 161-162.
Marsh, 1875a. On the Odontornithes, or birds with teeth. American Journal of Science, Series 3. 10(59), 403-408.
Marsh, 1875b. Odontornithes, or birds with teeth. The American Naturalist. 9(12), 625-631.
Marsh, 1880. Odontornithes: a monograph on the extinct toothed birds of North America. United States Geological Exploration of the 40th Parallel. Washington, DC: U.S. Government Printing Office. 201 pp.
Shufeldt, 1915. Fossil birds in the Marsh Collection of Yale University. Transactions of the Connecticut Academy of Arts and Sciences. 19, 1-110.
Howard, 1955. A new wading bird from the Eocene of Patagonia. American Museum Novitates. 1710, 25 pp.
Martin, 1987. The beginning of the modern avian radiation. Documents des Laboratoires de Geologie de la Faculte des Sciences de Lyon. 99, 9-20.
Elzanowski, 1995. Cretaceous birds and avian phylogeny. Courier Forschungsinstitut Senckenberg. 181, 37-53.
Clarke, 1999. New information on the type material of Ichthyornis: Of chimeras, characters and current limits of phylogenetic inference. Journal of Vertebrate Paleontology. 19(3), 38A.
Clarke, 2000. Ichthyornis and Apatornis reappraised. Vertebrata PalAsiatica. 38(suppl.), 9.
Clarke, 2002. The morphology and systematic position of Ichthyornis Marsh and the phylogenetic relationships of basal Ornithurae. Ph.D. dissertation, Yale University, New Haven, CT. 532 pp.
Hope, 2002. The Mesozoic radiation of Neornithes. In Chiappe and Witmer (eds). Mesozoic birds: Above the heads of dinosaurs. Berkeley: University of California Press. 339-388.
Clarke, 2004. Morphology, phylogenetic taxonomy, and systematics of Ichthyornis and Apatornis (Avialae: Ornithurae). Bulletin of the American Museum of Natural History. 286: 1-179.

Ceramornis Brodkorb, 1963
C. major Brodkorb, 1963
Late Maastrichtian, Late Cretaceous
Lance Formation, Wyoming, US
Holotype- (UCMP 53959) proximal coracoid
Comments- Hope (2002) notes this taxon shows a few plesiomorphic charadriiform-like characters, but lacks charadriiform synapomorphies.
References- Brodkorb, 1963. Birds from the Upper Cretaceous of Wyoming. in Sibley (ed.), Proceedings of the 13th International Ornithological Congress. American Ornithologists' Union. pp. 50-70.
Hope, 2002. The Mesozoic radiation of Neornithes. in Chiappe and Witmer, eds. Mesozoic Birds: Above the Heads of Dinosaurs. 339-388.

Gallornis Lambrecht, 1931
G. straeleni Lambrecht, 1931
Berriasian-Hauterivian, Early Cretaceous
Auxerre, France
Holotype- humeral fragment, proximal femur
Comments- Hope (2002) considers this an avian based on the presence of an elevated trochanteric crest and an anteroposteriorly expanded antitrochanteric facet.
References- Lambrecht, 1931. Gallornis straeleni n. g. n. sp., ein Kreidevogel aus Frankreich . Bulletin de Musee Royal d'Histoire Naturelle de Belgique. 7, 1-6.
Hope, 2002. The Mesozoic radiation of Neornithes. in Chiappe and Witmer, eds. Mesozoic Birds: Above the Heads of Dinosaurs. 339-388.

Iaceornis Clarke, 2004
Definition- (YPM 1734 <- Ichthyornis dispar, Struthio camelus, Tetrao major, Vultur gryphus) (new)
Other definitions- (YPM 1451 <- Ichthyornis dispar, Struthio camelus, Tetrao major, Vultur gryphus) (modified from Clarke, 2004)
= "Iaceornis" Clarke, 2002
Comments- Clarke (2004) accidentally defined Iaceornis identically to Apatornis, so I have provided the definition that was intended as a substitute until a formal correction is published.
References- Clarke, 2002. The morphology and systematic position of Ichthyornis Marsh and the phylogenetic relationships of basal Ornithurae. Ph.D. dissertation, Yale University, New Haven, CT. 532 pp.
Clarke, 2004. Morphology, phylogenetic taxonomy, and systematics of Ichthyornis and Apatornis (Avialae: Ornithurae). Bulletin of the American Museum of Natural History. 286: 1-179.
I. marshi Clarke, 2004
Definition- (the species that includes YPM 1734) (Clarke, 2004)
= "Iaceornis marshi" Clarke, 2002
Early Campanian, Late Cretaceous
Hesperornis Zone of the Smoky Hill Chalk Member of the Niobrara Formation, Kansas, US
Holotype- (YPM 1734) dorsal rib, scapulae (52.5 mm), coracoids (24 mm), partial furcula, incomplete sternum, proximal radius, radiale, ulnare, carpometacarpus (36 mm), phalanx II-1 (14 mm), phalanx II-2 (13 mm), ilium (50 mm; lost), pubis (32 mm; lost), ischium (lost), partial femur, incomplete tibiotarsus, fibula (28 mm; lost), fragments
Diagnosis- (after Clarke, 2004) hooked acromion (also in Apsaravis and Lithornithidae).
Other diagnoses- Clarke (2004) listed the strongly tapering omal furcular tip as an apomorphy, but this is also present in Archaeorhynchus, Yixianornis, Anseriformes, Mirandornithes, many Charadriiformes, Gaviidae and Procellariimorphae.
Comments- This specimen was discovered in 1877 and originally referred to Apatornis celer by Marsh (1880), though it is not comparable to the Apatornis holotype. Because of its completeness compared to the Apatornis holotype, it has been the basis of most authors' understanding of the genus since then, until Clarke separated it in 2002 (published in 2004) as Iaceornis. The pelvis which has been the most commonly illustrated portion of the specimen was lost prior to 1955. Both Marsh (1880) and Clarke (2004) described numerous features which differ from Ichthyornis, though Marsh and most authors until Clarke (2002, 2004) were wrong in believing the tibiotarsus lacked a supratendinal bridge. Howard (1955) thought YPM 1734 (as Apatornis) was similar to her new taxon Telmabates (described as a phoenicopteriform but now recognized as a presbyornithid anseriform) and might be referrable to Phoenicopteriformes itself, though she felt a more thorough review should take place before any official reclassification. Martin (1987) described cervical and humeral characters of Apatornis, but these elements are not preserved in the holotype or YPM 1734.
Iaceornis an ichthyornithine? Marsh (1880) considered YPM 1734 part of his Odontotormae when he described it, though never explicitly defended the view. It does share a keeled sternum, large wings and a carpometacarpus with Odontotormae as listed on page 187, but most Aves have these characters too. While this has been followed by most authors since, it seems more due to stratigraphy and tradition than actual character support.
Iaceornis an anseriform? Howard (1955) listed several characters she thought were similar in YPM 1734 and the presbyornithid Telmabates (though she viewed the latter as a phoenicopteriform, so viewed the characters as supporting placement of YPM 1734 in that order). The crossed coracoid sulci on the sternum are similar to not only Phoenicopterus and Telmabates, but also Ichthyornis, casuariids, Phaethon, Leptosomus, Steatornis, ciconiiforms, accipitrids and several other neoavians. The broadly rounded anterior sternal edge is plesiomorphic for ornithuromorphs. The short shaft and flaring sternal end of the coracoid were said to be similar to Telmabates, Phoenicopterus and the basal phoenicopteriform Paloelodus, but these are plesiomorphies which are also seen in such taxa as Gansus, Ichthyornis and Lithornis. The scapular facet of the coracoid being both round and deep was said to be most similar to Telmabates, and while similarly round facets are present in many ornithuromorphs and some look comparatively deep in figures (e.g. Cimolopteryx rara, Palintropus), the distribution of these features over Aves has yet to be studied. The supracoracoid foramen is in a similar position not only to Telmabates, but also to taxa such as Lithornis, Ichthyornis and Yixianornis. The scapula was merely said to resemble Telmabates, which is too vague for comment. A well developed ulnar facet on the proximal radius is also present in Limenavis and Eonessa in addition to Telmabates. The greatly expanded dorsal trochlea on the carpometacarpus is also present in the pangalliform Paraortygoides, Limenavis, Apsaravis and Yixianornis in addition to Telmabates. The carpal trochlea which extends distally to metacarpal III is indeed similar to Telmabates and the presbyornithid Teviornis and not seen in other Mesozoic ornithuromorphs. However, lithornithids and Paraortygoides share this feature as well. The extensor process of metacarpal I is fairly similar to Telmabates and Teviornis in being more elongate than any non-avian taxon and having a generalized triangular shape with proximally placed apex (as in Ichthyornis and Limenavis, though theirs are less elongate), but the lithornithid Pseudocrypturus shares this. According to Howard, in both YPM 1734 and Telmabates, the internal edge of metacarpal III is placed ventral to the ventral crest of the carpal trochlea, but this seems to be true in Apsaravis, Ichthyornis and Limenavis as well as in Teviornis. A trochanteric crest which extends proximal to the ilial facet on the femur is unlike other Mesozoic birds, but is seen in many Aves such as Paraortygoides, Pheonicopterus and the lithornithid Paracathartes.
Hope (2002) suggested the "short, angular" coracoid glenoid was similar to some anseriforms and other Aves, but indeed even Ichthyornis' could be described this way. The long, pointed acromion was said to be similar to anatoids, but is also seen in Ambiortus and Yixianornis. Hope also cited the laterally protruding distal end of the scapular glenoid "with surrounding shelf tapered distally" as a feature shared specifically with presbyornithids, though these are difficult to evaluate in most Mesozoic ornithuromorphs based on the literature alone. The ventromedial edge of the acrocoracoid process is raised as a lip which expands anteriorly in Iaceornis and Anatoidea, but this seems true of Apsaravis and Ichthyornis too. Finally, Hope states that Iaceornis' scapula is more similar to Presbyornis than Juncitarsus (a probable stem mirandornithine) in having a strongly concave dorsal edge anteriorly, but the edge in Iaceornis is actually convex and thus unlike both.
The evidence for an anseriform affinity seems weak, with only the scapular glenoid morphology described by Hope being potentially synapomorphic.
Iaceornis a non-avian ornithurine sensu Chiappe? Elzanowski (1995) placed YPM 1734 outside Aves based on two characters. The acromion was said to be longer than basal avians, but some (e.g. lithornithids, anatoids, Gallus, pelecanids, Cariama) have elongate acromia as well. The supratendinal bridge was said to be absent on the tibiotarsus, but this was a mistake by Marsh.
Clarke (2002, 2004) found Iaceornis to be outside Aves in her analysis based on four characters. There are no pneumatic foramina between the sternal rib articulations, but this is true of many avians as well, including apterygids, phasianoids, most Natatores, most charadriiforms and columbiforms. Similarly, the non-pneumatic coracoid is present in anatids, presbyornithids, and many pangalliforms including the basal Gallinuloides. Metacarpal III does not extend distally past metacarpal II, but this is also true in many Aves such as Pterocnemia, Telmatornis, Telmabates, Teviornis, Anas, Walbeckornis, Miodytes, Limnofregata, gruiforms and charadriiforms. Finally, the medial tibiotarsal condyle projects further anteriorly than the lateral condyle. This is found in numerous Aves however, including Anas, galliforms, most metavians, most Natatores, some charadriiforms and many others.
Despite being the conclusion of the only phylogenetic analysis to include Iaceornis, there is no unambiguous evidence the taxon is outside Aves. This is due in part to the huge variation in the clade, which was only represented in Clarke's matrix by two palaeognaths and four galloanserines. While it might be argued any character diagnosing Aves would be expected to reverse in some example, the preliminary comparisons above suggest some groups contain taxa which match all of Iaceornis' supposedly non-avian characters (e.g. anseriforms, galliforms).
Iaceornis closer to Aves than Ichthyornis? While Howard (1955) implicitly proposed this possibility when allying YPM 1734 with phoenicopteriforms, Clarke (2002, 2004) was the first to support it with characters found in basal avians. Paired intermuscular lines on the sternum and an intermetacarpal space ending distal to metacarpal I are also present in Gansus, which has always been resolved as basal to Ichthyornis in published analyses. The larger extensor process on metacarpal I and supratendinal bridge on the tibiotarsus are valid characters shared with neognaths and tinamids. Notably, lithornithids and ratites can lack all of these characters.
Hope (2002) noted the scapular facet on the coracoid was distal to the glenoid, unlike Ichthyornis. However, this also appears to be the case in Apsaravis and Yixianornis. Hope also stated the scapular glenoid was small and located anterolaterally, but the condition appears similar in Yixianornis. The scapular glenoid being much smaller than the coracoid glenoid does seem to be absent in non-avian ornithuromorphs where both can be observed though (Patagopteryx, Yixianornis, Ichthyornis), but is present in Tinamidae and Neognathae. Hope suggested the prominent acrocoracoid process was consistant with referral to Neognathae, but Gansus and Pseudocrypturus have similarly large processes.
While some of Clarke's and Hope's characters uniting Iaceornis with Aves have been found to be diagnostic of more inclusive clades thanks to recent discoveries (Gansus, Yixianornis, Apsaravis), the small scapular glenoid compared to the coracoid glenoid, large extensor process and supratendinal bridge do support this arrangement. Additionally, the well developed ulnar facet on the proximal radius, carpal trochlea which extends distally to metacarpal III, and trochanteric crest which extends proximal to the ilial facet on the femur noted by Howard as similar to Telmabates are only found in Aves (or in one case in Limenavis too, which is also closer to Aves than Ichthyornis) as well. Thus a placement closer to Aves than to Ichthyornis seems probable, while more exact affinities must await adding Iaceornis to a large matrix of avians. A relationship with galloanserines does seem plausible however, given the preliminary findings here.
References- Marsh, 1880. Odontornithes: a monograph on the extinct toothed birds of North America. United States Geological Exploration of the 40th Parallel. Washington, DC: U.S. Government Printing Office. 201 pp.
Howard, 1955. A new wading bird from the Eocene of Patagonia. American Museum Novitates. 1710, 25 pp.
Martin, 1987. The beginning of the modern avian radiation. Documents des Laboratoires de Geologie de la Faculte des Sciences de Lyon. 99, 9-20.
Elzanowski, 1995. Cretaceous birds and avian phylogeny. Courier Forschungsinstitut Senckenberg. 181, 37-53.
Clarke, 2002. The morphology and systematic position of Ichthyornis Marsh and the phylogenetic relationships of basal Ornithurae. Ph.D. dissertation, Yale University, New Haven, CT. 532 pp.
Hope, 2002. The Mesozoic radiation of Neornithes. In Chiappe and Witmer (eds). Mesozoic birds: Above the heads of dinosaurs. Berkeley: University of California Press. 339-388.
Clarke, 2004. Morphology, phylogenetic taxonomy, and systematics of Ichthyornis and Apatornis (Avialae: Ornithurae). Bulletin of the American Museum of Natural History. 286: 1-179.

Laornithidae Cracraft, 1972
Laornis Marsh, 1870
L. edvardsianus Marsh, 1870
Late Maastrichtian-Early Danian, Late Cretaceous-Early Paleocene
Hornerstown Formation, New Jersey, US
Holotype- tibiotarsus
Comments- Previously assigned to the Gruiformes, then assigned to the invalid family Graculavidae by Olson and Parris (1987).
References- Marsh, 1870. Notice of some fossil birds from the Cretaceous and Tertiary Formations of the United States. American Journal of Science, Series 2. 49, 205-217.
Olson and Parris, 1987. The Cretaceous Birds of New Jersey. Smithsonian Contributions to Paleobiology. 63, 22 p.

Palaeotringinae Wetmore, 1940
Palaeotringa Marsh, 1870
Comments- Previously assigned to the Gruiformes, then assigned to the invalid family Graculavidae by Olson and Parris (1987).
References- Marsh, 1870. Notice of some fossil birds from the Cretaceous and Tertiary Formations of the United States. American Journal of Science, Series 2. 49, 205-217.
Olson and Parris, 1987. The Cretaceous Birds of New Jersey. Smithsonian Contributions to Paleobiology. 63, 22 p.
P. littoralis Marsh, 1870
Late Maastrichtian-Early Danian, Late Cretaceous-Early Paleocene
Hornerstown Formation, New Jersey, US
Holotype- tibiotarsus
Reference- Marsh, 1870. Notice of some fossil birds from the Cretaceous and Tertiary Formations of the United States. American Journal of Science, Series 2. 49, 205-217.
P. vagans Marsh, 1872
Late Maastrichtian-Early Danian, Late Cretaceous-Early Paleocene
Hornerstown Formation, New Jersey, US
Holotype- tibiotarsus
Reference- Marsh, 1872. Preliminary description of Hesperornis regalis with notices of four other new species of Cretaceous birds. American Journal of Science, Series 3. 3, 360-365.

“Palaeotringa” vetus Marsh 1870
Late Maastrichtian-Early Danian, Late Cretaceous-Early Paleocene
Hornerstown Formation, New Jersey; Lance Formation, Wyoming, US
Holotype- (ANSP 13361) distal tibiotarsus
Referred- (AMNH 25221) distal tibiotarsus
Comments- Olson and Parris (1987) removed this from Palaeotringa and synonymized it with Telmatornis priscus, but Hope (2002) noted it differs from charadriiformes in several characters. She found gruids were most similar, along with idiornithids and Telmabates (a presbyornithid).
References- Marsh, 1870. Notice of some fossil birds from the Cretaceous and Tertiary Formations of the United States. American Journal of Science, Series 2. 49, 205-217.
Olson and Parris, 1987. The Cretaceous Birds of New Jersey. Smithsonian Contributions to Paleobiology. 63, 22 p.
Hope, 2002. The Mesozoic radiation of Neornithes. in Chiappe and Witmer, eds. Mesozoic Birds: Above the Heads of Dinosaurs. 339-388.

unnamed avian (Kakegawa, 1998)
Campanian, Late Cretaceous
Orannai Formation, Japan
Material- (NSMJ coll.) sacrum, scapula, pelvis, fibula, pedal phalanx
References- Kakegawa, 1998. The Late Cretaceous Aves from Wakkanai, Hokkaido. (Kagawa University, March 1998). Master's Thesis.
Kakegawa, 1998. A Late Cretaceous aquatic bird from Hokkaido Japan. SVPCA.

undescribed avian (Hope, 2002)
Late Maastrichtian, Late Cretaceous
Lance Formation, Wyoming, US
Material- (UCMP 53960) two cervical vertebral fragments
Comments- Questionably referred to Torotix by Brodkorb in the UCMP catalog.
Reference- Hope, 2002. The Mesozoic radiation of Neornithes. in Chiappe and Witmer, eds. Mesozoic Birds: Above the Heads of Dinosaurs. 339-388.

Palaeognathae Pycraft, 1900
Definition- crown (Struthio camelus + Tinamus major) (Gauthier and de Queiroz, 2001)

Limenavis Clarke and Chiappe, 2001
L. patagonica Clarke and Chiappe, 2001
Campanian-Maastrichtian, Late Cretaceous
Allen Formation, Patagonia, Argentina
Holotype- (PVL 4731) distal humerus, proximal radius, proximal and distal ulna, radiale, partial ulnare, proximal and distal carpometacarpus, incomplete phalanx II-1, fragments
Diagnosis- (after Clarke and Chiappe, 2001) three fossae on the proximal surface of the dorsal supracondylar process of the humerus (also in Ichthyornis, Lithornis and Torotix); attachment of the pars ulnaris of the trochlea humeroulnaris on the proximal ulna developed as a pit-shaped fossa; scar of the ligamentum collaterale ventrale of the ulna proximodistally elongate, extending down the caudal margin of the brachial impression (also in Podiceps, Gavia, Balaeniceps, Grus, Numenius and Burhinus); deep infratrochlear fossa proximal to pisiform process on carpometacarpus (also in Ichthyornis, Lithornis, Podiceps, some procelariiforms, Rallus and cuculiforms); pisiform process with its proximal surface at approximately the same level as the proximal surface of metacarpal I.
Other diagnoses- Clarke and Chiappe (2001) also included the deep tendinal groove of the ulnare in their diagnosis, but this is present in most Aves except ratites, Chauna, possibly galliforms, and some diving taxa.
Comments- The holotype was discovered in the mid 1980's but only described in 2001 by Clarke and Chiappe. Those authors used a matrix consisting mostly of forelimb characters to place Limenavis as a carinate more derived than Ichthyornis, but less so than Lithornis and Aves. Clarke (2002) scored Limenavis in her large cladistic analysis and found it to be a carinate more derived than Ichthyornis, but less than Iaceornis and Aves (including Lithornis), agreeing with the results of the earlier study.
Limenavis a carinate? Clarke and Chiappe (2001) placed Limenavis closer to Aves than Ichthyornis based on two characters. The articular surface of the dorsal ulnar condyle is proximally truncated and the carpal tubercle of the ulna is absent. Neither are known for non-carinates, and at least the latter is also untrue in Apsaravis, though each does exhibit some variation within Aves.
Clarke (2002) placed Limenavis closer to Aves than Ichthyornis because its metacarpal I extensor process is supposedly more projected, but this seems to be untrue. The projection perpendicular to the carpometacarpus shaft from the medial concavity in metacarpal I (compared to the width from the medial condyle of metacarpal I to the lateral carpometacarpal edge) is 18% in Ichthyornis and 16% in Limenavis. Limenavis' is more robust and more highly angled anteriorly, but the distribution of these attributes is as of yet unstudied.
Thus one character places Limenavis in Carinatae and another places it closer to Aves than Apsaravis.
Limenavis outside Aves? Only one character in Clarke and Chiappe's (2001) study supports its exclusion from Lithornis+Aves - metacarpal III ends proximal to metacarpal II. This is also found in anseriforms, stem galliforms, Phaethon, Mesitornis, Pterocles, gaviids, procelariiforms, steganopodes and charadriiforms. Four additional characters support placing Limenavis and Lithornis outside Aves, but as other analyses are consistant in placing Lithornis within Aves, these could equally well support placing Limenavis in Lithornithidae. Of these characters, the loss of two small fossae on the dorsal supracondylar tubercle of the distal humerus and loss of a deeply excavated infratrochlear fossa of the carpometacarpus are forelimb simplifications that may have been lost in crown paleognaths simply due to their reduced wings. The third character (lateral margin of manual phalanx II-1 straight) is also found in Neoaves in their matrix, making the strongly convex margin equally likely to have converged in crown palaeognaths and galloanserines as opposed to being basal for Aves. The last character (interosseal groove absent on distal carpometacarpus) is distributed sporadically throughout Aves, being present in Gallus, Anas and charadriiforms in their matrix for instance.
Clarke (2002) only used one different character to exclude Limenavis from Aves + Iaceornis (here viewed as an avian)- the less projected extensor process on metacarpal I. However, they note that various neoavians have equally low processes, and palaeognaths including lithornithids do as well.
In conclusion, all of the proposed characters to exclude Limenavis from Aves are widespread in that clade, with five of the six being present in Lithornis. It may most parsimoniously be a lithornithid, though any firm conclusions on its affinities await a more detailed comparison to basal avians.
References- Clarke and Chiappe, 2001. A new carinate bird from the Late Cretaceous of Patagonia (Argentina). American Museum Novitates. 3323, 1-23.
Clarke, 2002. The morphology and systematic position of Ichthyornis Marsh and the phylogenetic relationships of basal Ornithurae. Ph.D. dissertation, Yale University, New Haven, CT. 532 pp.

Neognathae Pycraft, 1900
Definition- crown (Pluvialis apricaria <- Struthio camelus, Tinamus major) (Gauthier and de Queiroz, 2001)

Piksi Varricchio, 2002
P. barbarulna Varricchio, 2002
Campanian, Late Cretaceous
Two Medicine Formation, Montana, US
Holotype- (MOR 1113) distal humerus, incomplete ulna (~100 mm), proximal radius
Diagnosis- (after Varricchio, 2002) large dorsal epicondyle on the humerus subequal to the dorsal condyle; flexor process of the humerus with a proximodistally angled wall; large dorsal cotyla on the ulna, twice as broad as the ventral cotyla; dorsal cotyla on the ulna with an elongate outline; ulna shaft lacking quill knobs.
brachial fossa on distal humerus; m. humerotricipitalis groove present on distal humerus; well developed olecranal fossa.
Comments- Originally described as a ornithothoracine of uncertain, but probably basal, relationship.
Reference- Varricchio, 2002. A new bird from the Upper Cretaceous Two Medicine Formation of Montana. Canadian Journal of Earth Sciences. 39(1), 19-26.

Qinornis Xue, 1995
Q. paleocenica Xue, 1995
Danian-Selandian, Paleocene, Paleogene
Fangou Formation, Shanxi, China
Holotype- (XD78sh048.3) (adult) tarsometatarsus (42 mm), phalanx II-1 (8.3 mm), phalanx II-2 (6.5 mm), pedal ungual II (2.4 mm), phalanx III-1 (9.3 mm), phalanx III-2 (7 mm), phalanx III-3 (5.8 mm), pedal ungual III (3.3 mm), phalanx IV-1 (6.85 mm), phalanx IV-2 (3.3 mm), phalanx IV-3 (3.5 mm), phalanx IV-4 (3.3 mm), pedal ungual IV (2.85 mm)
Paratypes- ....(XD78sh048.1) distal tibiotarsus
....(XD78sh048.2) incomplete tibiotarsus (~56 mm)
Comments- The type material was discovered in 1977-78 and described by Xue in 1995 as incertae sedis within birds. Xue considered the solid tarsometatarsus, incomplete tarsometatarsal fusion and open distal vascular foramen indicated the taxon either more basal than Aves or a subadult perhaps related to Charadriiformes or Gruiformes. Mayr (2007) thought the material was adult due to the fused distal tarsals and well defined distal articular surfaces, so considered it a possibly non-avian ornithuromorph based on the incomplete tarsometatarsal fusion. This would be the first bird outside the crown group Aves to be recognized in the Tertiary, which is why it is included in this otherwise Mesozoic theropod website. It has yet to be included in a phylogenetic analysis.
References- Xue, 1995. Qinornis paleocenica - a Paleocene bird discovered in China. Courier Forschungsinstitut Senckenberg. 181, 89-93.
Mayr, 2007. The birds from the Paleocene fissure filling of Walbeck (Germany). Journal of Vertebrate Paleontology. 27(2), 394-408.

Galloanserae Sibley et al., 1988
Definition- crown (Gallus gallus + Anser anser) (Gauthier and de Queiroz, 2001)

Pangalliformes Clarke, 2004
Definition- (Gallus gallus <- Anser anser) (Clarke, 2004)
Diagnosis (after Clarke, 2004)- asymmetrical development of the edges of the trochlea of metatarsal III.
References- Clarke, 2004. Morphology, phylogenetic taxonomy, and systematics of Ichthyornis and Apatornis (Avialae: Ornithurae). Bulletin of the American Museum of Natural History. 286: 1-179.

Austinornis Clarke, 2004
Definition- (Austinornis lentus <- Gallus gallus, Crax rubra, Megapodius freycinet) (Clarke, 2004)
= "Austinornis" Clarke, 2002
A. lentus (Marsh, 1877) Clarke, 2004
Definition- (the species that includes YPM 1796)
= Graculavus lentus Marsh, 1877
= Ichthyornis lentus (Marsh, 1877) Marsh, 1880
= "Austinornis" lentus (Marsh, 1877) Clarke, 2002
Late Cretaceous
Austin Chalk, Texas, US
Holotype- (YPM 1796) distal tarsometatarsus
References- Marsh, O.C. 1877b. New fossil vertebrates. American Journal of Science, 3rd. ser., 14: 249-256.
Marsh, O.C. 1880. Odontornithes: a monograph on the extinct toothed birds of North America. United States Geological Exploration of the 40th Parallel. Washington, DC: U.S. Government Printing Office, 201 pp.
Clarke, J.A. 2002. The morphology and systematic position of Ichthyornis Marsh and the phylogenetic relationships of basal Ornithurae. Ph.D. dissertation, Yale University, New Haven, CT, 532 pp.
Clarke, 2004. Morphology, phylogenetic taxonomy, and systematics of Ichthyornis and Apatornis (Avialae: Ornithurae). Bulletin of the American Museum of Natural History. 286: 1-179.

Anseriformes

Anatoidea

Anatalavis
A. rex

Vegavis Clarke, Tambussi, Noriega, Erickson and Ketcham, 2005
V. iaai Clarke, Tambussi, Noriega, Erickson and Ketcham, 2005
Middle to Late Maastrictian, Late Cretaceous
lithostratigraphic unit K3 of the Cape Lamb deposits, Vega Island, Antarctica
Holotype- (MLP 93-I-3-1) two cervical vertebrae, five dorsal vertebrae, over six dorsal ribs, sacrum, scapula, coracoid, humeri (one proximal), distal radius, ulna, pelvis, femora, tibiotarsus, fibulae, partial tarsometatarsi
Diagnosis- (from Clarke et al., 2005) low ridge on the medial edge of the proximal tibiotarsus.
References- Noriega and Tambussi, 1995. A Late Cretaceous Presbyornithidae (Aves: Anseriformes) from Vega Island, Antarctic Peninsula: paleobogeographic implications. Ameghiniana. 32, 57–61.
Clarke, Tambussi, Noriega, Erickson and Ketcham, 2005. Definitive fossil evidence for the extant avian radiation in the Cretaceous. Nature 433: 305-308.

Presbyornithidae

Teviornis
T. gobiensis

Neoaves Sibley et al., 1988
Definition- crown (Passer domesticus <- Gallus gallus, Anser anser) (Gauthier and de Queiroz, 2001)

unnamed neoavian (Brodkorb, 1963)
Late Maastrichtian, Late Cretaceous
Lance Formation, Wyoming, US
Material- (UCMP 53969) quadrate
Comments- Brodkorb (1963) referred this to Cimolopteryx rara within Charadriformes, but Hope (2002) noted it was not a charadriiform. The separated otic head is a character of neoavians and a few other taxa (Shuvuuia, Confuciusornis, Enaliornis), but the first two differ in lacking a pterygoid condyle. Hope noted Elzanowski et al. are working on the specimen.
References- Brodkorb, 1963. Catalogue of fossil birds. Part 1 (Archaeopterygiformes through Ardeiformes). Bulletin of the Florida State Museum, Biological Sciences. 7(4), 179-293.
Hope, 2002. The Mesozoic radiation of Neornithes. in Chiappe and Witmer, eds. Mesozoic Birds: Above the Heads of Dinosaurs. 339-388.

Metaves Fain and Houde, 2004

Coronaves Fain and Houde, 2004

Pelecaniformes Sharpe, 1891
Diagnosis- (after Hope, 2002) ventral rim of brachial fossa very narrow; attachment for ventral collateral ligament small; flexor process very short.

Torotigidae Brodkorb, 1963
Diagnosis- brachial fossa very deep and well defined; brachial fossa excavates ventral condyle.

Novacaesareala Parris and Hope, 2002
N. hungerfordi Parris and Hope, 2002
Late Maastrichtian-Early Danian, Late Cretaceous-Early Paleocene
Hornerstown Formation, New Jersey, US
Holotype- (NJSM 11302) distal humerus, proximal radius, partial ulna, fragments
Diagnosis- (modified from Parris and Hope, 2002) humeral shaft slightly flattened craniocaudally; brachial fossa distinctly tripartite, divided by pronounced crests into the more proximal brachial fossa proper and a ventral and dorsal supracondylar fossa; brachial fossa proper divided into a shallow proximal shelf and much deeper dorsal pit; broad flexor process.
Comments- Olson and Parris (1987) tentatively assigned this specimen to Graculavidae. Parris and Hope (2002) note it closely resembles Torotix except for the broad flexor process, presbyornithids except for the narrow ventral brachial depression rim, pelecaniformes except for the unflared ventral epicondyle and flexor process, and both presbyornithids and pelecaniformes except for the craniocaudally flattened shaft (unknown in Torotix) and the more distally extended brachial fossa. As Hope (2002) tentatively referred Torotix to Pelecaniformes, Novacaesareala is questionably placed as a torotigid pelecaniform here.
Although Ford emmends the species name to hungerfordorum because it was named after multiple people, but such emmendations aren't allowed according to the 1999 ICZN.
References- Olson and Parris, 1987. The Cretaceous Birds of New Jersey. Smithsonian Contributions to Paleobiology. 63, 22 p.
Hope, 2002. The Mesozoic radiation of Neornithes. in Chiappe and Witmer, eds. Mesozoic Birds: Above the Heads of Dinosaurs. 339-388.
Parris and Hope, 2002. New interpretations of the birds from the Navesink and Hornerstown Formations, New Jersey, USA (Aves: Neornithes). In Zhou and Zhang (eds.). Proceedings of the 5th Symposium of the Society of Avian Paleontology and Evolution, Beijing, 1-4 June 2000. 113-124.

Torotix Brodkorb, 1963
T. clemensi Brodkorb, 1963
Late Maastrichtian, Late Cretaceous
Lance Formation, Wyoming, US
Holotype- (UCMP 53958) distal humerus
Diagnosis- (after Parris and Hope, 2002) differs from Novacaesareala in having a narrow flexor process.
Comments- Assigned to Phoenicopteriformes by Brodkorb (1963), it was later placed in Charadriiformes (Olson and Feduccia, 1980; Olson, 1985), and most recently to Pelecaniformes by Hope (2002). the latter was based on several characters- ventral rim of brachial fossa very narrow; attachment for ventral collateral ligament small; flexor process broad and very short; sites for M. flexor carpi ulnaris and pronator profundus oriented ventrally; ventral epicondyle extended only slightly ventrally. However, Parris and Hope (2002) state the flexor process is narrow, unlike pelecaniformes and Novacaesareala.
Hope (2002) notes Brodkorb questionably referred two cervical vertebral fragments to Torotix (see entry under undescribed avian).
References- Brodkorb, 1963. Birds from the Upper Cretaceous of Wyoming. in Sibley (ed.), Proceedings of the 13th International Ornithological Congress. American Ornithologists' Union. pp. 50-70.
Olson and Feduccia, 1980. Presbyornis and the origin of the Anseriformes (Aves, Charadrimorphae). Smithsonian Contribs. Zool. 323, 24 pp.
Olson, 1985. The fossil record of birds. 79-239. in Farner, King and Parkes (eds.). Avian Biology. vol VIII. Academic Press, New York.
Hope, 2002. The Mesozoic radiation of Neornithes. in Chiappe and Witmer, eds. Mesozoic Birds: Above the Heads of Dinosaurs. 339-388.
Parris and Hope, 2002. New interpretations of the birds from the Navesink and Hornerstown Formations, New Jersey, USA (Aves: Neornithes). In Zhou and Zhang (eds.). Proceedings of the 5th Symposium of the Society of Avian Paleontology and Evolution, Beijing, 1-4 June 2000. 113-124.

Phalacrocoracidae Bonaparte, 1853

unnamed phalacrocoracid (Hope, 2002)
Late Maastrichtian, Late Cretaceous
Lance Formation, Wyoming, US
Material- (AMNH 25272) femur (~47 mm)
Comments- Hope (2002) refers this specimen to Phalacrocoracidae based on several characters-
Differs from other phalacrocoracids in the angular truncation of the trochanteric crest.
Reference- Hope, 2002. The Mesozoic radiation of Neornithes. in Chiappe and Witmer, eds. Mesozoic Birds: Above the Heads of Dinosaurs. 339-388.

undescribed phalacrocoracid (Kurochkin, 1995)
Maastrichtian, Late Cretaceous
Nemegt Formation, Mongolia
Material- (PIN coll.) scapula
Comments- Hope (2002) confirms Kurochkin's (1995) assignment of this specimen to Phalacrocoracidae based on- coracoid tubercle absent (also in other suloids); impression for M. deltoideus minor deep and recurved around the tip of the acromion; acromion elongate, broad, flat and recurved at tip.
References- Kurochkin, 1995. Synopsis of Mesozoic birds and early evolution of Class Aves. Archaeopteryx. 13, 47-66.
Kurochkin, 1995. The assemblages of the Cretaceous birds in Asia. In Sun and Wang (eds.). Sixth Symp. Mesozoic Terrestrial Ecosystems and Biota, Short papers. China Ocean Press. 203-208.
Hope, 2002. The Mesozoic radiation of Neornithes. in Chiappe and Witmer, eds. Mesozoic Birds: Above the Heads of Dinosaurs. 339-388.