Hidden, protected.
Ancient bird beneath acid,
DNA preserved.
DNA from extinct species can be hard to get – obtaining bone or tissue samples is tricky and degradation of those samples over time can result in vast swathes of the genome missing or heavily fragmented.
Yet, as a new study by Oswald et al (2019) suggests, there are circumstances where samples can be remarkably preserved across hundreds and even thousands of years.
The study used bones found in Sawmill Sink, a blue hole in the Bahamas. The Sawmill Sink has a top layer of fresh water, a hydrogen sulfide layer and then a bottom layer of saltwater. The hydrogen sulfide layer forms a barrier that limits UV light and oxygen from getting to the lower saltwater. As a result, the various bones found on floor of the blue hole are remarkably well preserved.
Oswald et al (2019) were able to recover a nearly complete mitochondrial genome from a 2,500 year old bone of an extinct bird species – Caracara creightoni. Genetic analysis of the ancient DNA suggests that the species is sister to a clade containing the Northern Crested Caracara and the Southern Crested Caracara, birds of prey in the Falconidae family found in Central and South America. The work highlights the huge potential for similarly recovered fossils to illuminate our understanding of species and populations in the past.
The title of this sciku is Pickled – Not Pickled. This refers to the hydrogen sulfide layer in Sawmill Sink which forms sulfuric acid where it comes into contact with the fresh water layer above, making it extremely hard for divers to get through and discover the bones beneath. Whilst the bones themselves were not in the sulfuric acid, they were preserved by it making them in essence pickled whilst not actually being pickled.
Original research: http://dx.doi.org/10.1016/j.ympev.2019.106576