Theravada Don't Practice Mahayana Nor Vajrayana

I refer to ME6102 Mahayana Buddhism, Chapter 1, Page 1, Para 1, Line 4 talk about one practice Mahayana without practicing Theravada and goes on to say similar as for the Vajrayana. However, in my opinion, this is not true for Theravada.

The Theravada always maintains that their suttas (Nikaya) and practices are authentic, authoritative and most original and most pure.

They adhere very closely to this practice and we can say there is no Mahayana nor Vajrayana element in their mind.

tan boon ann

it is not obvious

In appearance, the theravada does not follow any kind of practice from mahayana (nor vajrayana)
Peter Santina said that the Buddhism is like a big tree with the same root and many branches. The Mahayana is not a break point but a continuity. In my opinion, these school are alike and dissimilar at the same time. it depends of the point of view. I we see the differences, they are very different. But if we see the similarities, so, they are really similar.
The "hinayana" is the trunk of the all mahayana schools. The theravada is the background of the mahayana but theravada does not recognize the mahayana doctrines. They do not recognize the mahayana sources nor the sutras as saddharmapundarikasutra or lankavatarasutra, because it is not the authentic Buddha's teaching. The theravada school has been more rigid to include new elements.
however, both schools were practiced together by many centuries. Many Chinese pilgrims did not see differences between them (Hirakawa, history of indian Buddhism, ch 16, the origins of Mahayana)
May be, in developed stage, some Mahayana elements were included by Theravada.