Sanz and Buscalioni, 1992. A new bird from the Early Cretaceous of Las Hoyas, Spain, and the early radiation of birds. Palaeontology. 35, 829-845.
This paper described Sanz and Buscalioni's new bird Concornis lacustris, which has since been redescribed (Sanz et al., 1995) as an enantiornithine. It included a very small phylogenetic analysis.
Sanz and Buscalioni illustrated a cladogram from an analysis that excluded Enantiornithes and Ambiortus. Then they illustrated two more trees which included those taxa, but differed in which was closer to Ornithurae.
|--non-avian theropods `--Aves |--Archaeopteryx `--Euornithes |--Iberomesornis `--+--Concornis `--+--Enantiornithes |--Ambiortus `--Ornithurae |--Hesperornithiformes `--Carinatae
However, the text indicates that when Enantiornithes and Ambiortus were added, 36 most parsimonious trees resulted. Twenty-one of these had hesperornithines as the most basal birds after Archaeopteryx, while many of the others "placed Ambiortus or the Enantiornithes in an unlikely branching." Running the matrix though PAUP confirms that the true strict consensus tree is a polytomy-
|--non-avian theropods `--Aves |--Archaeopteryx `--Euornithes |--Iberomesornis |--Concornis |--Enantiornithes |--Ambiortus |--Hesperornithiformes `--Carinatae
Non-avian theropods- Which theropods were used to code from is never specified.
Enantiornithes- Iberomesornis and Concornis were not yet recognized as enantiornithines, but the authors did include the Lecho Formation material (including Enantiornis and what would later be named Lectavis, Yungavolucris, Soroavisaurus and Martinavis pricei), Avisaurus and the at-the-time unnamed Neuquenornis.
Carinatae- This is based on Cracraft's use of the term, for Ichthyornis and Aves. It is not at all certain this clade would exclude Ambiortus or Hesperornithes.
1. Ambiortus has a slender radius (~50% of ulnar width; Kurochkin, 1999), while carinates should be polymorphic since Ichthyornis has a thick radius (72%; Clarke, 2004).
3. This is a composite character involving both intermetacarpal space width and distal fusion between metacarpals II and III. They do not seem correlated, as Ichthyornis has a narrow intermetacarpal space but distal fusion, while many theropods have a broad intermetacarpal space and no fusion. Furthermore, the authors' intermediate state for Concornis (metacarpals II and III closely joined distally but not fused) is no longer seen in any taxon, since Concornis was later found to have distal fusion (Sanz et al., 1995). The intermediate state is deleted and only fusion is coded for. Contra the authors, Enantiornis and Neuquenornis lack distal fusion (Chiappe and Walker, 2002), so Enantiornithes is recoded. Whether Ambiortus has distal fusion is unknown due to poor preservation (Kurochkin, 1999).
4. This is another composite character involving the number of phalanges on
manual digits II and III, the length of manual phalanges, and the presence of
manual unguals. They are not always correlated, as Concornis (Sanz et
al., 1995) and Ichthyornis (Clarke, 2004) are both now known to have
unguals, but short phalanges and a reduced number of phalanges in digit III.
Modern Aves also often have unguals on digits I or (more rarely) II (Fisher,
1940). Concornis and Carinatae are both rescored as polymorphic.
Ambiortus is also scored polymorphic, as it has an ungual on
digit II at least, but also short phalanges like other derived birds (Kurochkin,
1999). With some minor partial exceptions (e.g. tyrannosaurids and Compsognathus
lacking more than one phalanx on digit III; "Ingenia" having
short phalanges), theropods known at the time show the plesiomorphic state,
so are still coded that way.
6. Avimimus has a fully fused tibiotarsus with well developed distal condyles (Kurzanov, 1987), so theropods are rescored as polymorphic. Sereno (2000) determined Iberomesornis has a fully fused tibiotarsus and that the prior identification of proximal tarsals was due to breakage.
7. This is a composite character involving both the distal divergence of metatarsals II and IV and also the ginglymoidy of the metatarsals. New preparation reveals the trochlea of Concornis to be in contact distally much like Iberomesornis and Archaeopteryx (Sanz et al., 1995). Hesperornithines like Enaliornis and Baptornis generally have highly transversely compressed metatarsals, but metatarsal II is divergent posteriorly, so they are retained as being apomorphic. Regarding ginglymoidy, many deinonychosaurs (e.g. Dromaeosaurus, Deinonychus, Velociraptor, Troodon) have ginglymoid metatarsals II and/or III (e.g. Ostrom, 1969), so theropods are recoded as polymorphic.
9. This character is confusing as it is called "reversal of first digit of foot", but the states are defined as the proximodistal placement of the hallux. These are not correlated, as many deinonychosaurs have distally placed but unreversed halluces. It is here coded as described in the states, which leaves theropods as plesiomorphic since the basal paravians with distally placed halluces had yet to be described.
10. Hesperornithines are recoded as polymorphic, as Hesperornis has non-strut-like coracoids (Marsh, 1888).
11. This is another composite character, combining interclavicular angle with the presence of a hypocleidium. Many taxa such as Ichthyornis, Ambiortus and many Aves have a low angle but no hypocleidium (Clarke, 2004; Kurochkin, 1999). Thus Ambiortus and Carinatae are recoded as polymorphic. Many theropods also have broad furculae with large hypocleidia, like oviraptorids (Barsbold, 1983). Theropods are recoded as polymorphic due to this. Neuquenornis has a low angle and hypocleidium (Chiappe and Calvo, 1994), so enantiornithines are coded as being apomorphic. Hesperornis has a broad interclavicular angle with no hypocleidium (Marsh, 1880), so hesperornithines are recoded as plesiomorphic.
12. Iberomesornis had a sternal keel at least posteriorly (Sereno, 2000), so is coded with an uncertainty polymorphy (state 1 or 2 present). Enantiornithines are kept coded as having a fully developed keel based on Neuquenornis, though it is ironic now that we know almost every other enantiornithine had a posteriorly restricted one.
13. Velociraptor (Norell et al., 1997) has a sternum much longer than its coracoids, so theropods are recoded as polymorphic. Iberomesornis is unknown, as its anterior sternum is unpreserved (Sereno, 2000). A better way to measure sterna should have been used, as taxa with strut-like coracoids need much longer sterna to count for this character than taxa like non-avialan theropods and Archaeopteryx.
14. Enantiornithines considered by Sanz and Buscalioni were not known to have pygostyles, so they should be recoded as uncertain.
General analysis conclusions- This analysis is mostly problematic for being so small. In addition, 5 of the 14 (36%) characters are composites, though at least none are correlated with other characters. One issue is that the trees illustrated are not the trees found by the analysis. The main tree only exists when two taxa are excluded, each of which has unique character combinations. Even when those taxa are included, the authors ignore most of the trees based on their preconceptions of what bird phylogeny should look like. If you're not going to trust the analysis over your intuition, why bother running one at all? In total, 22/112 (20%) of the states are miscoded. When corrected, the following tree results.
|--non-avian theropods `--Aves |--Archaeopteryx |--Hesperornithes `--Euornithes |--Iberomesornis |--Concornis |--Enantiornithes |--Ambiortus `--Carinatae
If Ambiortus and Enantiornithes are deleted a priori, as Sanz and Buscalioni did to make their resolved tree, Euornithes consists of two clades- Iberomesornis+Concornis and Hesperornithes+Carinatae. This is ironically the standard topology, though given only these characters and taxa, Ambiortus and Enantiornithes disrupt it.
Phylogenetic conclusions- The table shows the number of extra steps needed to accomodate each rearrangement using Sanz and Buscalioni's original matrix, and his recoded matrix. A negative number means the arrangement is already most parsimonious, but that many steps are needed to undo it.
|(theropods,Carinatae,Ambiortus(Iberomesornis,Concornis,Enantiornithes)) (Kurochkin, 1995)||1||1|
|(theropods,Iberomesornis,Concornis,Enantiornithes(Hesperornithes,Ambiortus,Carinatae)) (Sanz and Buscalioni, 1992)||0||2|
|(theropods,Iberomesornis(Concornis,Carinatae)) (Sanz and Buscalioni, 1992)||0||0|
Though the original matrix rejects Sauriurae with moderate support, the recoded one only rejects it weakly. No plausible bird topology is rejected, as the matrix is simply too small.
Experiments with controversial taxa- A basal ornithurine such as Confuciusornis may make Hesperornithes group with Carinatae instead of more basally. However, adding Confuciusornis to the modified matrix leaves Hesperornithes basal and Confuciusornis the sister taxon of Euornithes.