Palaelodus: transitional between flamingos and grebes?

A short break from our Prum et al. 2015 series
as we take a peek at the origin of flamingos and other basal neognath birds, which we’ll look at in greater depth tomorrow in part 3.

Traditionally
flamingos, like Phoenicopterus (Fig. 1), have been difficult to nest in bird cladograms. Flamingos seem to stand alone. Bird expert Gerald Mayr 2004 quoted Sibley & Ahlquist (1990), who wrote flamingos are “among the ‘most controversial and long-standing problems’” in phylogenetic analysis.

Bird expert
Cracraft (1981) made a luke-warm suggestion for stork affinities. Other bird experts, Olson and Feduccia (1980) liked stilts and avocets as relatives. They also suggested that flamingo-like Palaelodus (Figs. 2, 3) ‘may have occupied a more duck-like swimming niche than do typical flamingos’, The Galloanseres (chickens + ducks invalid clade) was considered, perhaps based on the long-legged duck Presbyornis.

Using molecules,
Prum 2015 and others before them nested the flamingo, Phoenicopterus, with the flightless grebe, Rollandia (Fig. 1). And now (hopefully) you see what I mean when I say, DNA does not recover testable or valid relations over long phylogenetic distances.

Figure 1. The flamingo, Phoenicopterus, compared to the grebe, Rollandia. DNA says these two are more closely related than any other tested taxa. The LRT reports they are not related.

Figure 1. The flamingo, Phoenicopterus, compared to the grebe, Rollandia. DNA says these two are more closely related than any other tested taxa. The LRT reports they are not related.

Using morphology
the large reptile tree, (LRT, 1026 taxa) nests the flamingo with the similarly proportioned, hook-beaked seriema, Cariama sisters to the terrestrial birds of prey, represented today by Sagittarius, the secretary bird. Here (Fig. 2), based on a long list of shared traits, it is possible to see how flamingos could gradually arise from seriemas.

Figure 2. Which taxa share more traits? Phoenicopterus, the flamingo nests with Cariama, the seriema in the LRT, but with Gavia in the Prum et al. DNA study. Gavia nests with Thalasseus, the tern in the LRT.

Figure 2. Which taxa share more traits? Phoenicopterus, the flamingo nests with Cariama, the seriema in the LRT, but with Gavia in the Prum et al. DNA study. Gavia nests with Thalasseus, the tern in the LRT.

Mayr 2004 wrote:
“A recent molecular analysis strongly supported sister group relationship between flamingos (Phoenicopteridae) and grebes (Podicipedidae), a hypothesis which has not been suggested before. Flamingos are long-legged filter-feeders whereas grebes are morphologically quite divergent foot-propelled diving birds, and sister group relationship between these two taxa would thus provide an interesting example of evolution of different feeding strategies in birds.”

Morphologicaly,
grebes are quite similar to loons, like Gavia (Fig. 2), which nests with terns and penguins in the Prum et al. tree AND in the LRT. (Wow! That’s a rare happenstance!)

Then Mayr 2006
found a taxon that had been around awhile Palaelodus ambiguus (Figs. 3–5), that morphologically linked flamingos to grebes. Mayr reports, “Since both grebes and †Palaelodidae are aquatic birds which use their hindlimbs for propulsion, it is most parsimonious to assume that the stem species of (Pan-)Phoenicopteriformes also was an aquatic bird which used its hind limbs for propulsion in the water (Mayr 2004). Palaelodus has “derived skull features of flamingos with leg adaptations for hindlimb propulsion found in grebes.”

Figure 3. From Mayr 2006, who wrote, "Palaelodus sp. (†Palaelodidae; uncatalogued specimen from Alliers in France in the collection of Forschungsinstitut Senckenberg). Note that the upper beak and part of the cranium in B are reconstructed."

Figure 3. From Mayr 2006, who wrote, “Palaelodus sp. (†Palaelodidae; uncatalogued specimen from
Alliers in France in the collection of Forschungsinstitut Senckenberg). Note that the upper beak and part of the cranium in B are reconstructed.”

In the LRT
stork-like Palaelodus (1.5m tall) nests with Rhynchotus, a tinamou. Like Rhynchotus, Palaelodus appears to be fully volant.

Figure x. Data used to score Palaelodus in the LRT. Note the very flamingo-like proportions, but this is a ratite.

Figure 4. Data used to score Palaelodus in the LRT. Note the very flamingo-like proportions, but this is a tall, gracile tinamou.

70 characters and 17 suprageneric taxa later, Mayr 2004 wrote:
“Previously overlooked morphological, oological and parasitological evidence is recorded which supports this hypothesis, and which makes the taxon (Podicipedidae + Phoenicopteridae) one of the best supported higher-level clades within modern birds. It is more parsimonious to assume that flamingos evolved from a highly aquatic ancestor than from a shorebird-like ancestor.” Do you see the fatal flaw here?

Figure x. From Mayr 2006, comparing the flamingo (above) to Palaelodus (middle) and the grebe (below) assuming a gradual transition of traits from grebe to flamingo.

Figure 5. From Mayr 2006, comparing the flamingo (above) to Palaelodus (middle) and the grebe (below) assuming a gradual transition of traits from grebe to flamingo that is not readily apparent because these taxa are not related to one another in the LRT.

Mayr employed 17 suprageneric taxa,
rather than generic taxa, even though his museum has a long list of bird skeletons in its collection. The Mayr 2004 cladogram is very poorly supported with most nodes failing to attain a Bootstrap score over 50. But it did nest Gavia with Phoenicopterus and grebes. Mayr also notes a parasite common to both grebes and flamingos alone among birds. Mayr did include tinamous in his analysis. So, I suppose character scoring is to blame here. Mayr’s hypothesis of relationships (Fig. 5) appears to be untenable. Many other taxa are closer to all three in morphology.

G. Mayr wrote via email upon seeing this cladogram:
“Hmm, to me the trees make little sense. If Palaelodus results within palaeognathous birds, many characters must be incorrectly scored. Furthermore, this exemplifies the pitfalls of laerge-scale cladistzic analyses.
Best wishes,
Gerald Mayr”

Unfortunately
this reply reflects the general view of PhDs. Large scale analyses, as readers know, test more possibilities, giving each taxon more opportunities to nest wherever they most parsimoniously fit.

References
Cracraft J 1981. Toward a phylogenetic classification of the recent birds of the world (Class Aves).Auk98: 681–714.
Mayr G 2004. Morphological evidence for sister group relationship between flamingos (Aves: Phoenicopteridae) and grebes (Podicipedidae). Zoological Journal of the Linnean Society. 140 (2): 157–169. doi:10.1111/j.1096-3642.2003.00094.x. ISSN 0024-4082.
Mayr G 2006. The contribution of fossils to the reconstruction of the higherlevelphylogeny of birds. Species, Phylogeny and Evolution 1 (2006):59–64.
Mayr G 2015. Cranial and vertebral morphology of the straight-billed Miocene phoenicopteriform bird Palaelodus and its evolutionary significance. Zoologischer Anzeiger – A Journal of Comparative Zoology. 254:18–26.
Milne-Edwards A 1863. Mémoire sur la distribution géologique des oiseaux fossiles et description de quelques espèces nouvelles. Annales des Sciences Naturelles (in French). 4 (20): 132–176.
Milne-Edwards, A 1867-1871. Recherches anatomiques et paleontologiques pour servir a l’histoire des oiseaux fos- siles de la France (Paris, G. Masson).
Olson SL, Feduccia A 1980a. Relationships and evolution of flamingos (Aves: Phoenicopteridae). Smithsonian Contributions to Zoology 316: 1–73.

wiki/Palaelodidae
wiki/Palaelodus
Dr. Gerald Mayr

Advertisements

2 thoughts on “Palaelodus: transitional between flamingos and grebes?

  1. Unfortunately
    this reply reflects the general view of PhDs. Large scale analyses, as readers know, test more possibilities, giving each taxon more opportunities to nest wherever they most parsimoniously fit.

    And as usual you don’t even consider the possibility that there might be any mistakes in your matrix. The LRT says it, you believe it, that settles it for you, whatever it may be.

  2. au contraire, mon ami. I’ve been repairing mistakes in the LRT over the past three weeks. I am always on the lookout for them. I’m disappointed that you tried to read my mind and failed to do so.

Leave a Reply

Fill in your details below or click an icon to log in:

WordPress.com Logo

You are commenting using your WordPress.com account. Log Out /  Change )

Google+ photo

You are commenting using your Google+ account. Log Out /  Change )

Twitter picture

You are commenting using your Twitter account. Log Out /  Change )

Facebook photo

You are commenting using your Facebook account. Log Out /  Change )

Connecting to %s

This site uses Akismet to reduce spam. Learn how your comment data is processed.