Parse this person name:

Dex Lensen (1831-1898, flourished 1850-1866)
user
first_name: Dex
last_name: Lensen
middle_names: []
temporal:
- start: 1831
  end: 1898
  type: life_span
- start: 1850
  end: 1866
  type: flourished
titles: []
extra_info: []
assistant