Cannot implicitly convert type error

My mode class and modelDTO  is given below. When I am trying to assign an object entity to another object entity the error is coming  Please help in my code

Author

 public class Author
    {
        [Key]
        [DatabaseGenerated(DatabaseGeneratedOption.Identity)]
        public int AuthorId { get; set; }

        [Required]
        [MaxLength(100, ErrorMessage ="First Name cannot be more than 100 characters")]
        public string FirstName { get; set; }

        [Required]
        [MaxLength(200, ErrorMessage = "Last Name cannot be more than 200 characters")]
        public string LastName { get; set; }

        [ForeignKey("CountryId")]
        public int CountryId { get; set; }
        public  Country Country { get; set; }
    }

Model

AuthorDTO
 public class AuthorDto
    {
        public int AuthorId { get; set; }
        public string FirstName { get; set; }
        public string LastName { get; set; }
        public int CountryId { get; set; }
        public CountryDto Country { get; set; }
        public IEnumerable<SelectListItem> CountryList { get; set; }
    }

public IActionResult GetAuthors()
        {
            var authors = _authorRepository.GetAuthors();

            if (!ModelState.IsValid)
                return BadRequest(ModelState);

            var authorsDto = new List<AuthorDto>();

            foreach (var author in authors)
            {
                authorsDto.Add(new AuthorDto
                {
                    AuthorId = author.AuthorId,
                    FirstName = author.FirstName,
                    LastName = author.LastName
                    Country = author.Country // Here error is coming 'Cannot implicitly convert type error'
                });
            }

GetAuthor Method

  public ICollection<Author> GetAuthors()
        {
            var authorList = _db.Authors.Include(c => c.Country).ToList();
        }