New plesiosaurs, lots of new plesiosaurs!

There was a time when I’d leap into tippy-tappy action at the first sniff of a newly named plesiosaur. Unfortunately, I haven’t been keeping Plesiosaur Bites up to date and a few new taxa have passed me by. Of course, when I say “a few”, what I really mean is we are swamped by the things. Little wonder I haven’t been able to keep up.

A few years ago I plotted a graph in my PhD thesis (Smith 2007, Figure 2.2.) to show the number of valid plesiosaur species and genera named in successive 20-year time intervals since 1821 (when the first plesiosaur was named [Plesiosaurus]). The data ended in 2007, the year I submitted my thesis, but showed that new taxa were being erected at a relatively steady rate throughout the 19th and 20th century (Figure 1). The rate started to pick up during the 1990s and I extrapolated the data into 2008-2020 based on the first seven years of the 21st century. I predicted 30 new genera in the period 2001-2020, which would represent a huge post-2001 leap in the number of new valid plesiosaurs. Well, so much for my crude calculations. It’s only 2012 and my ‘huge’ prediction has already been surpassed.

Figure 1. Tally of the number of new plesiosaur taxa per 20-year interval (from Smith 2007, Y-axis adjusted for direct comparison with Figure 2 below). 2001-2020 predicted based on 2001-2007 data.

n adjusted prediction for 2001-2020 based on the average rate of new taxa from 2001-2012 is actually pretty staggering (Figure 2).  62 new species and 51 new genera in a 20-year period? Can this be right, or are we about to reach a major drop off – were the last two years just out of the ordinary? Time will tell, but there are no signs yet of the bombardment slowing down, and if my previous prediction is anything to go by, the figure could even be an under-estimate.

Figure 2. Adjusted plot, with the 2001-2020 prediction based on 2001-2012 data.

So, how many plesiosaurs have been actually been named since 2008? Here’s a summary of all the new additions so the group:

Borealonectes (2008)

Nichollssaura, Gallardosaurus (2009)

Meyerasaurus, Alexeyisaurus (2010)

Abyssosaurus, Westphaliosaurus, Hauffiosaurus tomistomimus, Marmornectes,  Zarafasaura (2011).

Albertonectes, Anningasaura, Avalonnectes, Cryonectes, Lusonectes, Djupedalia, Dolichorhynchops tropicensis, Eoplesiosaurus,  Pliosaurus funkei, Spitrasaurus wensaasi, Spitrasaurus larsoni, and Stratesaurus (2012). So far.

Presuming I haven’t missed any (and please let me know if I have), that’s 22 new binomial taxa in the space of five years: 18 new genera and 21 new species (I’ve only listed the new species names above where they belong to existing genera, or where two new species have been erected within a new genus). I think this significant increase is due to several factors.

Firstly, historic plesiosaur specimens are receiving a considerable amount of renewed research attention. Many of the new taxa are based on fossils excavated in Victorian times. Anningasaura, Avalonectes, Eoplesiosaurus, Lusonectes, Strateosaurus, all fall into this category. Plesiosaurus continues to be exposed as the waste basket taxon it is.

Secondly, there have been numerous new discoveries in recent years. Sometimes these are the result of chance. Sometimes they are the result of a positive relationships that have developed between collectors or mining/quarrying businesses and palaeontologists. But often they are due to dedicated efforts to explore new strata or geographical areas. Djupedalia, Pliosaurus funkei (‘Predator X’ and ‘The Monster’), Spitrasaurus, and Zarafasaura, come to mind here.

Finally, more palaeontologists are looking at plesiosaurs in general. With fresh eyes. We are seeing differences where we weren’t even looking before, we are examining specimens more closely and more critically, we are applying new techniques and technologies to gain a greater understanding of plesiosaur anatomy, biology and phylogeny. It is inevitable that as more of us look, and as we look in more detail, we begin to unravel the complexity and diversity within Plesiosauria. Similar things are also happening in ichthyosaur research and mosasaur research, and I fully expect this ‘Mesozoic Marine Reptile Renaissance’ to continue into the foreseeable future. I’m looking forward to what the future holds in the world of plesiosaurs, even if I am struggling to keep up. One of these days I might even get around to writing about some of these new taxa and adding them to The Plesiosaur Directory…

References

Smith, A. S. 2007. Anatomy and systematics of the Rhomaleosauridae (Sauropterygia: Plesiosauria). PhD thesis. University College Dublin, 278pp. (Unpublished) (download PDF – 12.5mb )