{"id":82025,"date":"2025-08-20T08:52:09","date_gmt":"2025-08-20T08:52:09","guid":{"rendered":"https:\/\/www.newsbeep.com\/au\/82025\/"},"modified":"2025-08-20T08:52:09","modified_gmt":"2025-08-20T08:52:09","slug":"readers-wildlife-photos-why-evolution-is-true-2","status":"publish","type":"post","link":"https:\/\/www.newsbeep.com\/au\/82025\/","title":{"rendered":"Readers\u2019 wildlife photos \u2013 Why Evolution Is True"},"content":{"rendered":"

Today\u2019s photos come from reader Ephraim Heller, who took them in Brazil. Ephraim\u2019s text and captions are indented, and you can enlarge his photos by clicking on them.<\/p>\n

A Spurious Tale<\/p>\n

It was a typical birding day, squatting beside a water hyacinth-choked waste lagoon at a cattle ranch in Brazil\u2019s Pantanal watching giant rodents and caimans slither in the muck and waiting for something to happen involving birds.<\/p>\n

A capybara<\/a> (Hydrochoerus hydrochaeris), the largest living rodent, surfaces amongst the water hyacinth in a sewage lagoon:<\/p>\n

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I noticed southern lapwings and wattled jacanas squabbling along the shore. These are common birds but of interest to me because I have never been able to capture decent flight photos: they have evolved the ability to always fly directly away from the photographer. I slowly squat-walked along the banks and they allowed me to approach as they bickered and fought. I started snapping close-up photos with my big 540mm lens when I suddenly stopped dead in my tracks: that lapwing has nipples.<\/p>\n

A \u00a0southern lapwing<\/a> (Vanellus chilensis) displaying its \u201cnipples:\u201d<\/p>\n

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I got an A in my last biology class (AP high school bio in 1980) so I immediately grasped that the stale scientific consensus about the differences between birds and mammals was wrong. I guardedly approached Fito, our guide. Fito is one of the top 5 birding guides in all of Latin America and I had already established my credibility when I hired him and explained that my wife is a birder, but I just want to photograph the colorful and pretty ones. I showed him my photo and, in a tone as nonchalant as I could muster, asked \u201cWhat are those?\u201d<\/p>\n

\u201cWing spurs,\u201d said Fito.<\/p>\n

\u201cWing spurs,\u201d I sagely repeated. I had no idea what he was talking about.<\/p>\n

I went back to my station beside the sewage lagoon and began shooting again. Further photographic analysis reveals two important observations that could potentially cast doubt on my nipple theory: \u201cwing spurs\u201d indeed emanate from the lapwings\u2019 wings and they are retractable:<\/p>\n

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I turned my attention to the wattled jacanas\u00a0<\/a>(Jacana jacana) as a bully mercilessly chased away another jacana every time it landed. They ignored me as I shot. My shutter speed of 1\/2500 sec froze the action. I paused to check that my images looked all right when I make yet another discovery \u2013 wattled jacanas also have wing spurs:<\/p>\n

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I shuffle back to Fito.<\/p>\n

\u201cFito, are lapwings and jacanas closely related?\u201d<\/p>\n

\u201cNo.\u201d<\/p>\n

I walk over to my wife and show her my photos.<\/p>\n

\u201cRemember what I told you about hoatzins?\u201d she asks. We had seen lots of hoatzins the previous week in Brazil\u2019s Amazon. I remember that years ago my wife had told me about these strange birds that are born with claws on their wings. Before they can fly, they evade predators by dropping from their perches on branches overhanging the water, swim away from the danger, and then use their claws to climb back up a tree. As they mature their wing claws disappear.<\/p>\n

Adult hoatzin<\/a> (Opisthocomus hoazin) \u2013 no visible claws on their wings:<\/p>\n

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\u201cIsn\u2019t this an interesting example of convergent evolution?\u201d I say.<\/p>\n

\u201cMaybe it\u2019s not convergent evolution. Maybe it\u2019s an atavistic trait. From the dinos.\u201d<\/p>\n

While I hate it when my wife one-ups me on speculative nature theories, I have to admit that now I\u2019m intrigued. Do wing spurs represent a cool example of convergent evolution or an even cooler trait left over from the dinos?<\/p>\n

I do a quick internet search on wing spurs. Another bird we have just seen in Brazil also has wing spurs. Behold the southern screamer, presumably with its wing spurs retracted:<\/p>\n

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Now I was getting suspicious. My generation remembers the warning from James Bond\u2019s archenemy Auric Goldfinger in the Ian Fleming novel and 1964 movie Goldfinger: \u201cOnce is happenstance. Twice is coincidence. The third time it\u2019s enemy action.\u201d Lapwings, jacanas, hoatzin, and now screamers. What would Auric say?<\/p>\n

Herewith everything I\u2019ve subsequently learned about wing spurs.<\/p>\n

Wing spurs\u00a0are structurally distinct from talons or claws. Spurs usually project from the carpometacarpus, are covered by a keratin sheath, and are not used for perching or seizing prey. Unlike digit claws, which develop from the terminal phalanges, spurs are fixed, weapon-like appendages.<\/p>\n

Wing spurs are present in several bird orders but are relatively uncommon overall. Wing spurs seem to have evolved independently in several modern bird families. These include some species of screamers, steamer ducks, spur-winged geese, lapwings, jacanas, stone-curlews \/ thick-knees, and swamphens present in the new world, old world, and Australia. These families are only distantly related: lapwings, jacanas, and screamer clades all diverged at least 50 million years ago.<\/p>\n

Across taxa,\u00a0wing spurs\u00a0are primarily used as weapons\u2014employed in intraspecific combat, territorial defense, or predator deterrence.<\/p>\n

L. Rand published a detailed account of wing spurs in 1954 (available at: https:\/\/digitalcommons.usf.edu\/wilson_bulletin\/vol66\/iss2\/8<\/a>). He observes that \u201cspurs are projecting bony cores with an outer layer of horn, similar to the horns of cattle\u201d and, surprisingly, that \u201cthe horny covering of the wing spur, in some species, undergoes molt.\u201d He provides the following diagram of wing spurs in: (F) African jacana\u00a0(Actophilornis africanus); (G1 and G2) northern jacana\u00a0(Jacana spinosa); (H) southern lapwing\u00a0(Vanellus chilensis); and (I) Rodrigues solitaire\u00a0(Pezophaps solitaria).<\/p>\n

\u00a0<\/p>\n

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\u00a0<\/p>\n

In contrast to the wing spurs of modern birds, many basal avian dinosaurs, including\u00a0Archaeopteryx and Anchiornis, had\u00a0clawed fingers\u00a0on their wings.\u00a0These claws are\u00a0homologous\u00a0to the finger bones in modern birds, and in rare cases such as the hoatzin, vestigial claws are still present in juveniles. These are not carpal spurs, but true digit claws, aiding chicks in climbing until they fledge, when the claws are resorbed. The hoatzin lineage is highly divergent; molecular estimates suggest a split from other birds at least 64\u201370 million years ago, possibly earlier.<\/p>\n

Most importantly, both my wife and I were correct: hoatzin claws may be an atavistic trait related to the dinosaurs, while the wing spurs of other birds represent convergent evolution. How cool is that!<\/p>\n","protected":false},"excerpt":{"rendered":"Today\u2019s photos come from reader Ephraim Heller, who took them in Brazil. Ephraim\u2019s text and captions are indented,…\n","protected":false},"author":2,"featured_media":82026,"comment_status":"","ping_status":"","sticky":false,"template":"","format":"standard","meta":{"footnotes":""},"categories":[26],"tags":[64,63,128,338],"class_list":{"0":"post-82025","1":"post","2":"type-post","3":"status-publish","4":"format-standard","5":"has-post-thumbnail","7":"category-wildlife","8":"tag-au","9":"tag-australia","10":"tag-science","11":"tag-wildlife"},"_links":{"self":[{"href":"https:\/\/www.newsbeep.com\/au\/wp-json\/wp\/v2\/posts\/82025","targetHints":{"allow":["GET"]}}],"collection":[{"href":"https:\/\/www.newsbeep.com\/au\/wp-json\/wp\/v2\/posts"}],"about":[{"href":"https:\/\/www.newsbeep.com\/au\/wp-json\/wp\/v2\/types\/post"}],"author":[{"embeddable":true,"href":"https:\/\/www.newsbeep.com\/au\/wp-json\/wp\/v2\/users\/2"}],"replies":[{"embeddable":true,"href":"https:\/\/www.newsbeep.com\/au\/wp-json\/wp\/v2\/comments?post=82025"}],"version-history":[{"count":0,"href":"https:\/\/www.newsbeep.com\/au\/wp-json\/wp\/v2\/posts\/82025\/revisions"}],"wp:featuredmedia":[{"embeddable":true,"href":"https:\/\/www.newsbeep.com\/au\/wp-json\/wp\/v2\/media\/82026"}],"wp:attachment":[{"href":"https:\/\/www.newsbeep.com\/au\/wp-json\/wp\/v2\/media?parent=82025"}],"wp:term":[{"taxonomy":"category","embeddable":true,"href":"https:\/\/www.newsbeep.com\/au\/wp-json\/wp\/v2\/categories?post=82025"},{"taxonomy":"post_tag","embeddable":true,"href":"https:\/\/www.newsbeep.com\/au\/wp-json\/wp\/v2\/tags?post=82025"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}