Closing The Gaps - Early Bird Shows Evolution

The fossil bird with its revealing stomach contents (insert)
Credit: © Senckenberg

Eocene fossil is earliest evidence of flower-visiting by birds

We have an interesting discovery reported this week in Biology Letter of a fossil bird which seems to be the earliest known avian nectar-feeder. It shows how evolution is driven by environmental opportunity as diversifying species move into and exploit the opportunities offered by new and evolving niches as the ecosystem they are part of develops, and how cooperation is at least as likely an outcome as are arms races and competition as 'selfish' genes are selected naturally because they produce more descendants.

Two researches, Gerald Mayr of the Ornithological Section and Volker Wilde of the Palaeobotanical Section, of Senckenberg Research Institute and Natural History Museum Frankfurt, Germany have cooperated in examining a fossil bird (Pumiliornis tessellatus) from the middle Eocene of Messel found at Messel, Germany and have shown it to almost certainly be the first known example of a nectivorous bird.

It has long been recognised that flowering plants or angiosperms, and nectar-feeding insects co-evolved as symbiotic relationships - the insects get nectar and the plants get their pollen spread to other flowers of the same species. This process minimises the waste of untargeted wind-blown pollen dispersal and the environmental restrictions of using motile male gamete found in lower plants such as mosses, ferns and liverworts, all of which require a damp environment so the motile gametes have something to swim in.

It's easy to understand how this system could have evolved from crawling insects and ground-hugging plants to flying insects and the wide rage and form of flowering plants now free to move into drier habitats. All this took place prior to the 160 million years ago from when we have the first definite fossil record of flowering plants which are believe to have diverged from the gymnosperms 240-202 million years ago. The major period of rapid diversification seems to have been around 120 million years ago.

Pollen grains in the stomach.
See original paper for explanation.

Meanwhile, the first true birds were diverging from the theropod dinosaurs about 150 million years ago, so they grew up with flowering plants, so so speak, and these provided them with the same ecological niche some insects had moved into, most notably and probably initially a wasp from which the bees have evolved. It's not surprising therefore that some birds such as the humming birds moved into this niche becoming smaller and more bee-like in the process (as incidentally, some other insects such as moths and butterflies, have).

Abstract
Birds are important pollinators, but the evolutionary history of ornithophily (bird pollination) is poorly known. Here, we report a skeleton of the avian taxon Pumiliornis from the middle Eocene of Messel in Germany with preserved stomach contents containing numerous pollen grains of an eudicotyledonous angiosperm. The skeletal morphology of Pumiliornis is in agreement with this bird having been a, presumably nectarivorous, flower-visitor. It represents the earliest and first direct fossil evidence of flower-visiting by birds and indicates a minimum age of 47 million years for the origin of bird–flower interactions. As Pumiliornis does not belong to any of the modern groups of flower-visiting birds, the origin of ornithophily in some angiosperm lineages may have predated that of their extant avian pollinators.

Mayr. G. & Wilde. V.; Eocene fossil is earliest evidence of flower-visiting by birds; Biol. Lett. May 2014 vol. 10 no. 5 20140223; doi: 10.1098/rsbl.2014.0223

As the authors point out, this fossil only provides a minimum estimate for the evolution of ornithophilous (literally, bird-loving) plants but no pre-Eocene plants show any of the characteristics of ornithophilous plants and no earlier avian fossils show adaptation to a nectivorous diet. There is also an interesting reference to the remains of small insects amongst the pollen grains in the bird's stomach, possibly ingested accidentally, as occurs with present-day nectar feeders. However, this could give a clue about the evolution of nectar-feeding in this particular bird having possibly evolved from foraging for insects especially those exploiting the supply of nectar.

I wonder if creationists are able to explain why every single fossil meshes so neatly into our understanding of how evolution works, what it produces and the time-scale over which it operates, and never ever supports their special creation by magic a few thousand years ago notion. Every single discovery seems to be closing the gaps in which they try to fit their ever-shrinking little gods. That should be enough to convince any normal person that their daft notion is wrong, or at least to sow a few seeds of doubt about the wisdom and knowledge of the technologically backward and scientifically illiterate Bronze-Age hunter-gatherers who believed in magic and who came up with it in the first place.

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