Giraffes are one of the most iconic species that roam our planet, so you’re likely familiar with most of their quirks and eccentricities (seriously, what’s the deal with those ludicrously long necks?) – but did you know there’s not one but four species of the tallest living terrestrial mammal?

The long-necked creatures were long believed to belong to a single species – Giraffa camelopardalis – which is further divided into nine subspecies. However, back in 2016, a deep dive into their genetics revealed there are in fact four species: the Masai, northern, reticulated, and southern giraffe. Now, new research has further confirmed this distinction by analyzing giraffe skull morphology.

The Giraffe Conservation Foundation – alongside researchers from the University of Cape Town, Universidad Autónoma de Madrid, several European universities, and African government partners – have conducted a large study to shed more light on the gentle giants, with a view to ensuring their conservation.

The team 3D-scanned and analyzed 515 giraffe skulls found in African national parks, game farms, taxidermists, and museum collections around the world. As well as identifying distinct differences between male and female skulls – known as sexual dimorphism – the analysis revealed differences in line with the 2016 study. The four genetically distinct species also have unique cranial morphologies, thus confirming the existence of a quartet of giraffe species.

The differences are largely linked to bony horn-like structures on their skulls called ossicones. In the northern giraffe (G. camelopardalis), for example, the median ossicone is very high and pointy; whereas in the reticulated giraffe (G. reticulata), it is more hill-like; in the Masai giraffe (G. tippelskirchi), meanwhile, it is much smaller; and in the southern giraffe (G. giraffa), it is barely noticeable.

“This groundbreaking research highlights the value of science to increase our understanding of our natural world,” lead author Dr Nikolaos Kargopoulos said in a statement. “When I embarked on this project, I did not expect to find such clear differences in the skull shapes of giraffe – before I started looking more closely, I thought a giraffe is just a giraffe …”

With only around 117,000 giraffes remaining in the wild in Africa, the fact there are four unique species is crucial to inform efforts to protect them. The researchers highlight the importance of recognizing each taxon and call for conservation measures to focus on them individually.

“It is about time that the world stands tall for giraffe, in particular the IUCN, and changes the outdated taxonomy of giraffe to give them the status they deserve,” co-author Dr Julian Fennessy, Director of Conservation at the Giraffe Conservation Foundation, added. “Conservation efforts need to urgently target all four giraffe species – particularly those with precariously low numbers – before it is too late. Science is science and facts are facts. I hope that any debate around giraffe taxonomy can now finally be put to rest as we must act now to save each of these iconic giraffe species.”

The study is published in the journal PLOS ONE.